





Bulletin 24 


DEPARTMENT OF THE INTERIOR 
BUREAU OF MINES 


JOSEPH A. HOLMES, DrrRector 


BINDERS FOR COAL BRIQUETS 


INVESTIGATIONS MADE AT THE 
FUEL-TESTING PLANT 
Sd LOUIS, ‘MO: 


BY 


JAMES E. MILLS 


[Reprint of United States Geological Survey Bulletin 343] 





WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1911 





CONTENTS. 


SR dE OES ae an Sa es Meni Aa 2A 
MEI RG OIG £2 40% hele or wee ore vie Sate dan OKIE ae 2 se oid mabe 
IEEE TLL OE TT LO gas os on yo ae oe eel ccliihtae's soe % ane Mh 

Smmeeenrnmetin POO: DTICUCLAL. 1. 02). 2cis\s sis y= ho cating ede b hee eee ae 
Pe ee te eile eof Gok a ee wk clade dog tia wale heals on x ioe 
Hardness and toughness. ....... é eac (GS 16 Oncaea he ie SPAR ces OUR RoE NE d 
EN iii). cS a AMO Role evens ey eee ta mene 
RE rN Ne Whole Sha cimeddhews Co Gt aay Gis e Giggs de 22 Beg eke 
IIMs tear AN RE Wt IRON Os cue ca a el ae 
EMI eee NS a teen Soe TNS IES Ae 
MERIC Pa LW VAS a2 Pek hae PAL LR Re oh oe ous AEE 

MRM NOTNAT ROUGE ad sabe fo tiie Sra eiceiailk saseie gd stele a Geos ei pitai Aa SLi 
URES] GOES SEITE Pe bo pep ORE EE aI ee 
INP RSG Tne eer eee Ucn ae Ce 4 al aig eh larva louie oP 
RRORern i Weer er ee eee he a el og hale 4 els 8 alolal hr as wit ake 
SE SINC eg TOA OO CE Se ee eh a 

Piatra poverning the use of bindersii. 1.00. eid le ee eek 
Maximum cost allowable for binder....-........-... S iieel, Aas epiel «doe, 
RIE OTT DLIMICTE foc fo sais Ook els ye co sls a's ha ek on lee p ae ee ods 
Peeeworaualty of binderon the briquet...........:...-.2-:--54.-+-4.5 

MIRE EVEN VECUIO AL LON Sy aie hhc alas 2 wie die die ipaie wid Ba wn os Bae 
Physical relation of coal and binder....-.. 2 TIMI oy RNB ARE VaR Da 
Onalities of binder imparted to briquet.............20..220000.020000. 
RSE TERIOR LOCL Cot caine aise | bik ul Sp nan oats tt hed Ws Ua a a 
ANS AS CIPS oid 8s RA Ge Rainn RL LS gS haere ORES: PERNT 
MuNIIMEEEMIEMEIINLOY NOCCEGALY 6. 2. ds ees 2d oe nse ee tin eet ee end escsee 
MEINE REECE SS BOUL Pa yo cn Te vehi p 4 Se nin 2b 5 ol sietaiaiete ois Sie crete ale 
Percentage of voids.......-- ch bys ae aa i AAR Os te Dk Ay Lagat 
MEM IECCORUITID SV ALTSgts) Sa us stb 2. een a Se ee oak ogee eee ey 
SPREAD AIGTALONS weet in Soe eo ea di eit ths sel Puls Ww BN Ws DRO Ne 
imuornory investigations of various binders......-....--..---s0-2--5-e-eeeee- 
Beeenoasiand scope of the examination::........-2-...-...-02-0 shee ce en as 
Sererinacion of percentage of binder). 2.0... 3. kn ee ok. 
EEE CLOT CH COLOTONCE a. 25 fakes One ac naa d eke eeiae cm dim oe 5-3 
List of materials studied..........-. A EAS ay ho, (21, AA RIN Re IIR ’. 
EEE TEE a eS Renee Gab oe Qa nc Ai AA, Ru LR BARA LANNE UR MIAIRGTR 
PtH Spal Sedge Da atm a ae ae aig Sei SW pepe a 
ei EDS SENT Fh ARO ERS 8 SY GS en SE RP RRR SL ERTIBOY pt S W 
ERE OTM AL Wier, ata ala ee sis IES ye weds va Oh SBS DOAN 
CU SETI TS GN NEE ays Sg ra aa RG GE 
IEEE TOPICS Ge ae nha ial alin cit inal aii an eo oe 


4 CONTENTS. 


Laboratory investigations of various binders—Continued. 


Organic binders—Continued. 


Tars and ‘pitches. from coal... io) 220 ieee oe os 

Natural asphaltss, 2. 2s2.227 2 ee eed 
Petroleum productal +2 fi... .cu see ee eek. 
Additional experiments with mixtures. 2.02... 2... . See 
Experiments in briquetting without binders......................--- 
Results of tests in briquetting different coals..................---.-- 
Bibliography: 2... 6.002022)... ee ee 
Survey, publications on briquetting.. 2,-2.2. .-..-.-2 98 
Miscellaneous publications: . .: a9. e.-) sees... oe 
Indexer oe pase ae SER) 2 RE Oe SANs 


ILLUSTRATION. 


| Page. 
Fic. 1. Curve showing relation between percentage of binder and coherence of 
briquet.. 2 02.0. 2e sie taeevee ae ele eel ee 


19 


BINDERS FOR COAL BRIQUETS: 


INVESTIGATIONS MADE AT THE FUEL-TESTING PLANT, 
ST. LOUIS, MO.* 


By James E. Mitts. 


INTRODUCTION. 


THE COMMERCIAL PROBLEM. 


Coal, in the process of mining, transportation, and handling and 
on exposure to the weather, is subject to more or less disintegration. 
This disintegrated coal is usually called ‘slack’? and amounts often 
to a considerable percentage of the lump coal produced in the mines, 
If this slack coal is wasted the loss so occasioned ranges from 5 to 50 
per cent, or even more, of the total coal mined. It is therefore 
clear that the utilization of this waste slack coal becomes a serious 
economic consideration. 

When the coal is suitable for the production of coke, the utilization 
of the slack presents no difficulty, as it is in demand for that purpose. 
If the coal does not produce good coke, but cakes rather readily, the 
slack can be used for boiler purposes, as it fuses together more or less 
quickly, and burns on the furnace grate without great loss. Coal 
that cakes less readily can be burned on grates of special construc- 
tion. When so used it is more troublesome to handle, and the waste 
is greater than when lump coal is used. Consequently the price 
of much of the slack coal for fuel purposes ranges considerably lower 
than that of the lump coal from the same mine. 

The full value of this slack coal as fuel can be realized by first form- 
ing the coal into a coherent mass or briquet, such briquets, when of 
good quality, being equal to or of greater value than the original 





a The writer undertook the work herein reported, in 1905, at the fuel-testing plant of the United States 
Geological Survey, under the direction of Dr. Joseph Hyde Pratt, of the University of North Carolina, 
to whom he is greatly indebted for advice and suggestions, given not alone at the beginning but through- 
out the progress of the work. Acknowledgment is also due for suggestions given by Mr. A. A. Steel, 
of the University of Arkansas, and for the assistance of many individuals and corporations who have 
answered inquiries and furnished samples as desired. Incompiling this report and in laboratory work 
free use has been made of all available information thus acquired. 


5 


6 BINDERS FOR COAL BRIQUETS. 


lump coal from which the slack was derived. The object of the 
investigations herein reported was to determine as far as possible to” 
what extent the manufacture of briquets from slack coal may succeed 
commercially under the conditions existing in the United States. 

The problem of briquetting is not always that of how to make the 
best possible briquet, for the slack at hand may be of inferior quality 
and the best»possible binding material may be too expensive for the 
conditions prevailing in that particular locality. The problem is 
always to produce at a profit a briquet of satisfactory grade for the 
use intended. This problem will be made clearer by a brief summary of 
the available binders, followed by a preliminary discussion of the 
characteristics of a good briquet. 


THE KIND OF BINDER. 


Definite answer to the question ‘‘What is the best binder to use in 
making briquets?’’ depends, as repeatedly emphasized in this paper, 
on the locality, on the character of the coal, and on the purpose for 
which the briquets are intended. For purposes of a brief comparison 
consideration is given to the binders available for a coal which is 
fairly easy to briquet and which cakes rather readily. A few coals 
will briquet with somewhat less and others require greater percentages 
of binder, but an endeavor has been made in the following summary 
to strike a reasonable average. 

The experiments herein reported show that, in general, for plants 
situated where it can be obtained, the cheaneee binder will prove to 
be the heavy residuum from mnie often known to the trade as 
asphalt. Four per cent of this binder being sufficient, its cost ranges 
from 45 to 60 cents per ton of briquets produced. ‘This binder is 
particularly available in California, Texas, and adjacent territory. 

Second in order of importance comes water-gas tar pitch. Five » 
to six per cent usually proving sufficient, the cost of this binder ranges 
from 50 to 60 cents per ton of briquets produced. As water-gas pitch 
is also derived from petroleum, it will be available more Py 
in oil-producing regions. 

Third in order of importance is coal-tar pitch. Being derived from 
coal, this binder is very widely available. From 6.5 to 8 per cent will 
usually be required, and the cost ranges from 65 to 90 cents per ton 
of briquets produced. 

Of local importance, where the price permits, are natural asphalts 
and tars derived from wood distillation. The price of each of these 
binders varies greatly with the locality, but there are doubtless places 
where they could compete with the binders above mentioned. Wax 
tailings could be used with an easily caking coal, 

Pitch made from producer-gas tar is not yet on the market, but it 
will produce excellent briquets, with a lower percentage of binder 


INTRODUCTION. 7 


than other coal-tar pitches. It will doubtless be available in the 
future. 

Briquets excellent in all respects except that they are not water- 
proof can be made by using 1 per cent of starch as a binder, the cost 
of which is 20 cents per ton of briquets produced. Extra care is nec- 
essary in drying and handling these briquets, and this adds to their 
cost. 

The waste sulphite liquor from paper mills also produces excellent 
briquets except that they are not waterproof. At present it is a 
troublesome waste product dissolved in much water. Its utilization 
for this purpose will bear further investigation. 

Of inorganic binders, magnesia might be utilized, as its probable 
cost would not exceed 22 to 30 cents per ton of briquets produced. 
Other inorganic binders, while available as regards price, would not 
make first-class briquets. 

The briquetting of lignite coal offers a peculiarly difficult problem. 
If the lignite cakes in the fire, asphaltic residues from petroleum or 
water-gas tar pitch may be used as binder, larger percentages being 
required than for ordinary coals. The most promising binders for 
ignites that do not cake are starch, sulphite liquor, and magnesia. 
Lignites may be briquetted without binder if they are to be burned 
on grates specially constructed to overcome the tendency to fall to 
pieces in the fire. 

. Attention is called to the suggested method of deciding as to the 
value of coal-tar pitch for briquetting purposes. The method is like- 
wise applicable to asphalts and petroleum residues generally: (1) 
The pitch or tar is distilled and all oils coming off below 270° C. are 
rejected as being of no value; (2) the flowing point of the portion to 
be used in briquetting is determined (this should generally not be less 
than 70° C.); (8) the pitch is extracted with carbon disulphide. The 
smaller the amount of residual carbon the more satisfactory is the 
pitch. The less readily the coal cakes the higher must be the flowing 
point of the pitch. If a pitch cracker is used, the pitch to work 
successfully on a hot summer’s day must have a flowing point above 
120°C. In the winter pitch with a flowing point of 100° C. may be 
used. All softer pitches and asphalts have to be melted and mixed in 
liquid form with the coal. 

A pitch with a very high softening point, above 150° C., should be 
either thinned or superheated in the mixer. The efficient use of a 
binder depends very largely on the proper regulation of the conditions 
in the mixer. The presence of low-volatile compounds in the pitch 
to be used as a binder increases the smoke in burning; and also 
increases the tendency of the briquet to soften and crack open in 
advance of combustion, owing to the volatilization and escape of 
these compounds. 


g BINDERS FOR COAL BRIQUETS. 


The main problem in briquetting is to find a suitable binding mate- 
rial at sufficiently low cost. When the difference in price between 
the slack coal and the first-class lump coal is $1, the cost of briquetting 
should not exceed this amount. Of this the binder must cost less 
than 60 cents per ton, as the cost of manufacture averages about 40 
cents. To leave out of consideration the possible advantages in the 
use of briquetted coal over run-of-mine coal, due to the greater effi- 
ciency and smokelessness of briquets, it will probably not be neces- 
sary to pay any attention to binding materials costing $1.25 or more 
per ton of briquets produced. 


CHARACTERISTICS OF GOOD BRIQUETS. 
COHERENCE. 


The briquet should be sufficiently coherent. In France briquets are 
tested for coherence as follows:¢ 

One hundred and ten pounds of briquets are divided into 100 pieces of 1.1 pounds 
each, which are placed in a cylinder 36.22 inches in diameter and 39.57 inches in 
length. This cylinder is divided into three compartments by diametrical partitions 
and revolves at a speed of 25 revolutions per minute. After being charged, it is 
revolved for two minutes, and the contents are thereupon sifted upon a screen perfo- 
rated with holes 1.12 inches square. The proportion which does not pass through this 
screen indicates the degree of cohesive force, which, in the case of the French Admi- 
ralty tests, should reach 52 per cent, or if the fuel be intended for torpedo boat use, 
58 per cent. 

Briquets of any desired degree of coherence may be made by vary- 
ing the amount of binding material used in the briquet and by varying 
the pressure. An increase of either the binder or the pressure, of 
course, represents an added cost in manufacture. Experiments made 
by M. Wery, of Paris,’ with a Biétrix machine may be taken as 
illustrative: 


Effect on coherence of varying pressure and amount of binder. 













Pressure 











: Pressure 
Mardy t in pounds ot piteh Rpacnniehih 
square cen- abies im . used. obtained. 
timeter. 0 
1, 844 6 
2, 695 6 
3, 831 6 
1, 844 7 
2, 695 7 
3, 547 Tf 





Ordinarily briquets may be considered sufficiently coherent when 
the loss occasioned by dust and breakage involved in their use does 
not exceed 5 per cent. Both manufacturers and consumers should 
recognize the desirability of adapting the briquet to the use intended. 











a Briquets as fuel: Special Consular Report, vol. 26, p. 54. b Idem., p. 50. 


CHARACTERISTICS OF GOOD BRIQUETS. 9 
HARDNESS AND TOUGHNESS. 


The briquet should be sufficiently hard; but if too hard it is like- 
wise brittle, and therefore less coherent when subjected to rough 
handling. It is usually advantageous, therefore, to make the briquet 
of the minimum hardness that will suffice for the purpose in view. A 
briquet can be made harder by using a binder with a higher softening 
(melting) point. Consequently, if pitch is used, the most brittle 
pitch makes the hardest briquet. Moreover, a larger percentage of 
the more brittle pitch is usually required. 

The requirement of the French Admiralty is that the briquet should 
not soften at 60° C. (140° F.). Ordinarily it is sufficient that the 
briquet shall not soften on the hottest day, and shall behave satisfac- 
torily on burning. 

DENSITY. 


It is sometimes specified that the briquet should have a density of 
not less than 1.19. Perhaps a better standard would require the 
briquet to about equal in density the lump coal from which the slack 
was derived, thus ranging from 1.1 to 1.4. The density is increased 
by pressure. 

SIZE AND SHAPE. 


The convenience of a briquet for a given purpose, and hence the 
extent of its use, will depend largely on the size and shape. Atten- 
tion is therefore called to the following points: 

Heavy rectangular blocks allow a large output for the investment 
and are consequently cheaper to manufacture. They are convenient 
for storage. The French naval estimates show that 10 per cent more 
in weight of briquets can be stored in a given space than of lump coal, 
and the British Admiralty reports show a gain of as high as 20 per 
cent. Large rectangular briquets have the disadvantage of large 
smooth surfaces and are usually broken up when fed into furnaces, as 
this appears to promote combustion. ‘To facilitate the breaking they 
are pressed with grooves or perforations. This gives better air cir- 
culation but decreases the output and the possibility of storage by 
just so much. 

Prismatic shapes with rounded edges are most popular abroad. 
Hither these or ovoid shapes of less than 2 pounds weight are preferred 
for domestic use. The rounded edges cause much less dust and 
breakage on handling and insure good air circulation and thorough 
combustion, but are wasteful in space and make the briquet somewhat 
harder to ignite. | 

The output of hollow, cylindrical, polygonal, and_ball-shaped 
briquets abroad is small, the other shapes having proved more gener- 
ally preferable. 


10 BINDERS FOR COAL BRIQUETS. 
WEATHERING. 


The briquet should stand long exposure to the weather with but 
little deterioration. A dense briquet will stand the weather better 
than a porous one. In the process of manufacture ,briquets are 
liable to crack if they lack the proper proportion of binder, or if the 
binder and coal particles have been improperly mixed, or if the bri- 
quets are pressed too wet, or are insufficiently pressed. If the coal 
is finely ground, the briquet assumes a more dense and polished sur- 
face and is then more resistant to the weather. Cracks, however 
produced, allow the entrance of moisture and cause a rapid deteri- 
oration of the briquet on exposure to the weather. Lignite briquets, 
owing probably to the tendency of the lignite to absorb water and 
also to the more porous structure of the briquet, do not stand long 
exposure to the weather as successfully as other briquets. 

The binder used must be insoluble in water. The great obstacle 
to the successful use of starch, molasses, and sulphite-liquor residues 
as binders is their solubility, the cost of rendering the briquet water- 
proof being usually prohibitive. It is deserving of serious consider- 
ation whether or not in certain dry portions of the West, where fuel 
is scarce, the waterproofing of the briquet could not be dispensed 
with altogether during the dry season, and to a considerable extent 
during the rainy season by keeping the briquets under cover. 

With pitches, tars, etc., a slightly increased percentage of binder 
is necessary in briquets that are to stand long exposure to the weather. 
Further details are given under the discussion of the various binders. 


ABSORPTION. 


The briquet should not absorb more than about 3 per cent of mois- 
ture. The amount of moisture absorbed is increased when either the 
slack itself or the briquet is porous, or when the binder used has a 
tendency to attract moisture. 3 


BURNING QUALITIES. 


Readiness of ignition.—The ease with which a briquet will ignite 
depends largely on the slack used, but can be regulated to some 
extent. Large briquets ignite less readily than small ones. Sharp 
edges are an aid to ignition, though this advantage is not so great 
as to overcome the general preference for the prismatic and egg- 
shaped briquets. Briquets made from fine slack ignite less readily 
than those from coarser slack. A dense briquet is also more difficult 
to ignite. The use of an inorganic substance, such as clay or mag- 
nesia, as a binder, or as a constituent of the binder, tends to make 
the briquet ignite less readily. Increase of inorganic material—that 
is, ash—in the slack coal used produces the same result. 


CHARACTERISTICS OF GOOD BRIQUETS. 11 


Kind of flame.—The briquet should burn with a clear, intense 
flame, and without odor or smoke. The burning of the briquet and 
the flame produced, as well as the smoke given off, will depend largely 
on the quality of the slack coal used and on the completeness of the 
combustion. The completeness of combustion can be regulated to 
some extent in the manufacture of briquets by making them of a 
shape to insure a good air circulation and by the choice of a suitable 
binder. So far as the choice of a binder for this purpose is concerned, 
the principle involved may be summed up in the statement that the 
smoke does not depend on the total amount of volatile matter in the 
briquet, but only on that part of the volatile matter which escapes 
before it is heated to the kindling temperature. In other words, the 
binder should not volatilize before the temperature is sufficiently high 
to insure complete combustion of the gases formed. In general 
terms, therefore, a binder adds smoke in proportion to the amount 
of low-boiling constituents (oils, etc.) that it contains. 

Inorganic binders, of course, produce no smoke. Such organic 
binders as starch, molasses, or sulphite-liquor residues likewise do 
not volatilize until decomposed, and hence do not smoke, or smoke 
but little. Pitches, tars, and petroleum residues, when used as bind- 
ers, volatilize, and will cause smoke and possibly odor if the gases 
formed are not completely burned. Butitis quite possible to regulate 
the conditions, even when using these binders, in such a way that 
the briquets will produce less smoke than the lump coal from the 
screenings of which the briquet is made. ‘This is due to the regular 
shape of the briquet, which allows a better-regulated air supply, 
enabling more complete combustion to take place. This reduction 
of the smoke nuisance is one of the advantages to be derived from 
the use of briquets. 

Retention of shape.—The quality of retaining its shape in the fire 
is very important and depends on the properties of both the coal 
and the binder used in making the briquet. This point is discussed 
more fully in connection with the various coals and binders examined. 
The principle involved is very simple. The binder must hold the 
coal particles together until they are sufficiently softened to cohere. 
The temperature at which different coals soften or cake together 
varies greatly. Some bituminous coals cake readily at a low tem- 
perature, others less so. Semianthracite coals follow next in order, 
and then anthracite coals, some of the very hard anthracite coals 
with only a small amount of volatile matter showing little tendency 
to cake. Lignites as a class do not cake readily. Some, however, 
as those from Oklahoma or New Mexico, will cake sufficiently at a 
rather high temperature to hold themselves together. Others, as 
some California, Texas, or North Dakota lignites, show practically 
no tendency to soften or cake at any temperature. With such lig- 


LY BINDERS FOR COAL BRIQUETS. 


nites it is extremely difficult to make a briquet that will retain its 
shape in the fire. Briquets satisfactory for domestic use, when prop- 
erly managed, can be made from such lignites. These briquets 
might be used in a variety of manufacturing operations if a grate 
suitably adapted to the fire box is provided. For use in a locomotive 
they would be less suitable. 

With a readily caking coal, a binder that volatilizes (boils) at 
a comparatively low temperature may be used. With coals that 
cake at higher temperatures a less volatile binder must be used to 
obtain a satisfactory result in the fire. With a lignite that does not 
cake, the only binder that. will enable the briquet to retain its shape 
until completely consumed is an inorganic binder which does not 
volatilize at all—unless, indeed, sufficient binder is added to prac- 
tically coke the briquet. With such lignites, organic binders that do 
not volatilize, such as starch, molasses (in the form of waste residues 
from the sugar factories), sulphite-liquor residues from the paper 
mills, etc., give results that are fairly satisfactory, the briquet retain- 
ing its shape until the binder is itself decomposed. As the inorganic 
binders add ash and the other nonvolatile binders mentioned are not 
waterproof, it would seem generally better, wher commercially pos- 
sible, to mix a coal that will not cake of itself with a sufficient quan- 
tity of caking coal. Then when a suitable binder is used the briquet 
will retain its coherence in the fire by the softening of the caking coal 
used. The relation between the caking of a coal and its constitu- 
tion is not well understood. 

Percentage of ash.—The amount of ash left when the briquet is 
burned is the sum of that contained in the slack and in the binder 
used. Organic binders, as a rule, contain a smaller percentage of 
ash than the slack coal, and therefore slightly decrease the total per- 
centage of ash in the briquet. When inorganic binders are used the 
ash thus added is a decided disadvantage. 

In some foreign countries only 6 per cent of ash is permitted under 
many of the contracts for briquets. When the ash content of the 
slack exceeds 6 per cent it is therefore quite common abroad to wash 
the slack coal before briquetting. This saves freight on an incom- 
bustible material, saves binder, and gives in every way a better and 
more concentrated fuel. In this country, where good coal is so 
much cheaper than abroad, it will probably not usually prove feasi- 
ble to wash the slack coal. 


EVAPORATION RESULTS. 


Theoretically the heating value of a briquet is the sum of the heat- 
ing values of the coal and of the binder; and it can not possibly 
exceed this amount. Organic binders usually equal or exceed in 
heating value, weight for weight, the slack coal used. Usually, 


CONDITIONS GOVERNING THE USE OF BINDERS. 13 


therefore, they increase the total heat in a given weight of fuel, but 
owing to the small percentage of binder added, this increase is rela- 
tively slight. But the briquets have the advantage over the coal in 
that their burning is accompanied with less waste and they permit a 
better-regulated and more complete combustion to take place. In 
this way the heating value actually obtained from the fuel, weight 
for weight (and this, of course, is the important consideration), may 
be materially increased by the manufacture of the fuel into briquets. 
This increased heating value of the briquets over that of the slack 
used thus becomes a matter of practical importance. 

The evaporation results should at least equal those of the best 
lump coal from the screenings and dust of which the briquet was 
made. 


CONDITIONS GOVERNING THE USE OF BINDERS. 
‘ 
MAXIMUM COST ALLOWABLE FOR BINDER. 


The output of a briquet plant depends to a very great extent on 
the size of the briquets manufactured. The cost of labor depends 
greatly on the size and arrangement of the plant and on the wages 
paid, which will vary considerably in different localities. The price of 
slack coal and of the different binders is even more dependent on the 
locality. An approximate idea of the total. cost of manufacture, 
exclusive of the cost of the slack coal and the binder used, is here 
presented, in order to consider intelligently estimates which may be 
made of the maximum allowable cost of the binder, it being obviously 
useless to investigate a binder that could never be commercially used 
on account of its cost. E. Loze®% estimates the cost for manufacture 
in France at 33 to 40 cents per ton. Schorr? states that the cost in 
France is 24 to 34 cents per ton; in Germany, 22 cents to 24 cents; 
and in England, 24 cents. Estimates of the cost in the eastern and 
western parts of the United States are as follows: 


Estimated cost per ton of manufacture of briquets in the United States (exclusive of binder 
and of coal briquetted). 














Western | Eastern 

States. | States. 
ELIOT ONVGKOMSUACKING o.oo 5.c 52. cules Gas occu dees pee are desde seaeesecdtalisss s $0. 16 $0. 20 
ek a os n'a, a nse ot sin ste aio eh mdb miei h Whales bith att & oellehede on wimm bare hem aah’ . 006 OL 
POOP ONEN ars Vl. Sota Sok bt tebe acwb ek Pesce ae ce see come sce ane on claire Sreehne -O1 .O1 
re Eras i NS ew ciate aun he ena e dae Soa oetaey, its a Aha iaere Macias 04 WALT 
oa 9 a SRS IRR SS ss ee ee ae ae ga Seay 05 .10 
266 49 





Considering 30 to 50 cents per ton, therefore, as being approximately 
the cost of manufacture, it appears that when the difference in price 





a Eng. and Min. Jour., vol. 76, 1903, pp. 277, 431. 
6 Trans. Am, Inst. Min. Eng., vol. 35, 1904, p. 100. 


14 BINDERS FOR COAL BRIQUETS. 


between the slack coal and the first-class lump coal is $1, the binder — 
must cost less than 50 to 70 cents per ton. Good briquets would 
probably find in many places a market at a price slightly advanced 
over that of the corresponding lump coal from the screenings of 
which the slack was derived. Yet it is evident that the main problem 
in briquetting is to find a suitable binding material at a cost suffi- 
ciently low. A binding material costing as much as $1 per ton of 
briquets produced could be used profitably in but few places in the 
United States. Even allowing for future possible greater variation 
in price between the coal and the slack it is not necessary to pay 
attention to any binding material costing above $1.25 per ton of 
briquets produced. 


QUALITIES DESIRED IN BINDERS. 


It is needless to say that a desirable binder should make a good 
briquet and should make it cheaply. The characteristics of a good 
briquet have already been pointed out. It will not, perhaps, be too 
great a repetition to summarize here, in the approximate order of 
their importance, the desirable qualities of a binder, as follows: 

1. It must be sufficiently cheap to make the manufacture of briquets 
profitable. 

2. It must bind strongly, producing a briquet sufficiently hard, 
but not too brittle. 

3. It must hold the briquet together satisfactorily in the fire. 

4. It must produce a briquet sufficiently waterproof to stand the 
conditions of use. 

5. It should not cause smoke or foul smelling or corrosive gases, 
or foul the flues. 

6. It should not increase the percentage of ash or clinker. 

7. It should increase, or certainly not diminish, the heat units 
obtainable from a given weight of fuel. 


EFFECT OF QUALITY OF BINDER ON THE BRIQUET. 


SCOPE OF THE INVESTIGATIONS. 


The behavior of a large number of different coals with a few binders 
and of a few coals with a large number of different binders has been 
very carefully studied. Tests were made with each coal and with 
each binder until the percentage of binder required to produce a satis- 
factory briquet with that coal was determined. The behavior of the 
briquets in the fire and, when necessary, in water was noted. The 
binders used were examined as to their chemical or physical prop- 
erties and such modification of the binder was made as seemed likely 
to produce more efficient results. 

The conclusions that follow are submitted as the net result of the 
studies thus outlined. 


CONDITIONS GOVERNING THE USE OF BINDERS. 15 


PHYSICAL RELATION OF COAL AND BINDER. 


The relation between the coal and the binder is purely physical. 
Chemical action, if coming into play at all, is so slight in amount as 
to be wholly negligible. Moreover, the properties of the binder are 
not greatly changed by the mutual solubility, or surface action, of coal 
and binder at the surface of the coal. 

The above statements are shown to be true by the fact that if the 
coals are arranged in a series according to the percentage of one binder 
required, they will retain that same order when other binders are used, 
even when these binders are of the most diverse nature. The experi- 
ments of Constam and Rougeot® show that the soluble portion of 
the binders (various pitches) could be extracted from the briquets 
practically quantitatively with carbon disulphide, and that this 
reagent extracted at the most only 0.7 per cent from the coal. 

The properties of the briquet are the properties.of the coal plus the 
properties of the binder, and the combination of the two in briquetting 
does not materially change the properties of either. Not only is this 
observation true of briquets at ordinary temperatures, but it is also 
confirmed by their behavior in the fire. The decomposition of the 
binder caused by the heat may alter its character to some extent, but 
never, so far as the writer has observed, sufficiently to mask its original 
character. The action of the briquet in air and in water also con- 
firms the truth of the above observation. 


QUALITIES OF BINDER IMPARTED TO BRIQUET. 


If the binder is brittle the briquet will be relatively brittle at the 
same temperature. ‘Thus rosin, hard pitches, asphalts, cements, etc., 
make briquets that are hard, but they break easily from a sharp 
blow or fall. Liquids such as coal tar, creosote, asphalt tar, etc., 
make briquets that do not break easily from a fall, but they yield so 
readily to pressure as to be useless. Comparable percentages of 
binder being used, the toughest briquet—that is to say, the briquet 
that will stand the most rough usage—is made with a binder that at 
ordinary temperature twists easily and pulls into threads, that will 
cut with a knife rather than break, and that flows very slowly, taking 
some time to assume the shape of the container. Such a binder is 
sufficiently elastic not to be brittle and is sufficiently stiff not to yield 
to climatic changes of temperature. Binders that have been exam- 
ined fulfilling this condition are pine-wood tar (12), water-gas tar 
pitch (39), wax tailings (40), and residuums from petroleum, often 
designated as asphalts (37 A, 37 B, and 37C). Satisfactory briquets 
are made with 3 to 5 per cent of the above binders. If the coal does 





a Zeitschr. f. angew. Chemie, vol. 17, No, 26, p. 1. 
b Numbers refer to list on p. 22, 


16 BINDERS FOR COAL BRIQUETS. 


not cake readily a binder with a higher melting point would be 7 
required to make the briquet retain its shape in the fire. | 


BEHAVIOR WHEN HEATED. 


The binder will soften when in the briquet as soon as it is heated 
to the temperature at which it softens when outside of the briquet. 
Such softening will not be so apparent, however, for the binder exists 
in the briquet as a very thin coating over the grains, and if it melts 
to a thick, sticky liquid, rather than to a limpid one, its cohesive 
power in the state of a liquid is still very great. But it must be 
borne in mind that all briquets have a temperature of maximum 
weakness in the fire. This temperature lies in the interval between 
the melting or destruction of the binder and the softening of the coal 
as it commences to cake. If the coal softens at a high temperature 
the binder must melt at a relatively high temperature to give satis- 
factory results in the fire. If the coal does not cake at all, then the 
binder must not melt at all, or be destroyed by the heat, if a per- 
fectly coherent briquet at all temperatures is desired. Only inor- 
ganic binders could fulfill this condition, and their use is objectionable. 
Organic binders that do not melt, such as starch, etc., give the best 
results in the fire with a noncaking coal, but are not waterproof. 

In a furnace the briquet does not become thoroughly heated 
throughout at the same time, and as the binder near the surface of 
the briquet melts and passes out as a gas, the binder in the next 
interior layer of the briquet to some extent takes its place, and so on. 
In this way the briquet is held together until the coal at its surface 
softens and cakes. When this happens the briquet commences to 
regain its strength and with many coals soon becomes stronger than 
when placed in the fire. 

The binder will volatilize out of the briquet and appear as a gas 
as soon as it reaches the temperature at which it boils when outside 
of the briquet and in the pure condition. If this happens much below 
the kindling temperature of the gas some smoke and odor will be 
caused, and the smoke and odor may to a large extent be taken as 
proportional to the low-boiling oils in the binder—at least so far as 
the smoke is caused by the binder and not by the coal. 


SOLUBILITY. 


If the binder used is to any extent soluble in water the briquet 
will not withstand exposure to wet weather. The binder will go into 
solution as surely, though more slowly, in the briquet, as when it 
exists in the pure condition outside of the briquet, unless the briquet 
is in some way rendered waterproof. 


CONDITIONS GOVERNING THE USE OF BINDERS. Ly. 
QUANTITY OF BINDER NECESSARY. 
SURFACE TO BE COATED. 


The fact that the binder exists unchanged in the briquet, its office 
being solely to coat the grains, fill up void spaces between the grains, 
and by its adhesive and cohesive properties hold the briquet together, 
points to the following conclusions. 

The amount of binder required will depend on the amount of sur- 
face to be coated, and the amount of surface will depend on the size 
of the grains, on their density (that is, the density of the dry coal), and 
on the capillary pores in the coal. The theoretical relation between 
the amount of surface to be coated, the size of the grains, and the 
density of the coal can be easily eOpNIEH 

Let w=weight of coal taken. Suppose the grains of coal to be 
spheres, and let r = radius of the sphere. Let d = density of the coal. 
Then the volume of the sphere is $ 77°. The weight of the sphere 
is 4 ard. The number of grains of coal in the weight of coal 


taken is a. The surface of each grain is 4 7 7’, and the total 
Me yy 3t0 
surface to be coated is —— 


rd. 

That is, the amount of surface to be coated varies inversely with 
the density of the coal and inversely with the diameter of the grains. 
The same law can be shown to apply whatever the shape of the grains. 

The practical bearing of this relation is important. Thus, suppose 
a coal of density 1.4 requires 6 per cent of pitch to make a satisfac- 
tory briquet. Then a coal of density 1.1, other things being the same, 
would require 7.63 per cent of pitch, or 1.63 per cent more pitch than 
is required by the denser coal. This is one reason why lignite coal 
with a low specific gravity requires more binder than the average 
coal. 

The variation in the size of the grains of coal has an even greater 
influence on the amount of binder required. The table below shows 
the relative amount of surface to be coated in coal slack of varying 
degrees of fineness: 


Relation between size of grains and amount of surface. 














Number of | Diameter Size of Relative Number of | Diameter Size of Relative 
meshes to of wire | mesh (mil-| amount of meshes to of wire |mesh (mil-| amount of 

inch. (inch). limeters). | surface. inch. (inch). limeters). | surface. 
i. ee eee 0.131 25. 400 1 SOs. es eee 0. 00575 0. 230 110 
io . 103 12. 700 2 1003S ese . 00450 .170 150 
rE) See 079 6. 350 4 UO Saye cee . 00235 . 085 300 
ie 027 2. 1D hea Wane oe oe eel eae 5 ee Ne . 005 5,080 
ys 01650 1.000 DO eae mee ee Re PRR ee . 0025 10,160 
Sl) ee 01375 670 SUOMI oe eo Oa eee oS . 00075 33, 900 
40 Seek 01025 500 OU or iwereme 4. ASRS UNE Na a eee eb . 00025 101, 600 

BO 2. cae 310 81.9 











98315°—Bull. 24—11——2 


18 BINDERS FOR COAL BRIQUETS. 


It will thus be seen that coal slack which will just pass a 20-mesh 
sieve has 6.35 times as much surface to be coated as the same weight 
of slack crushed so as to pass a screen of }-inch mesh, and that coal 
passing a 200-mesh sieve has 75 times the surface of coal just passing’ 
the t-inch mesh. The very finest dust, having a diameter of 0.00025 
millimeter, has 25,400 times the surface of coal just passing the 
1-inch mesh. 

This consideration is not purely theoretical. The remark of 
Wagner,’ that it took 20 per cent of pitch to briquet certain fine coal 
dust, is illustrative of its practical bearing. The degree of fineness of 
the slack coal used is one of the main factors in determining the per- 
centage of binder necessary to produce a satisfactory briquet. 

To illustrate this point, mention is here made of a fact shownelater, 
that all coal-tar pitches contain a certain amount of carbon (soot), 
which, being in a very finely divided condition, is not only inert so far 
as binding the coal together is concerned, but itself requires a binder. 
Owing to the dustlike condition of this carbon its effect on the binding 
power of the pitch for the coal is most marked. Thus, although a 
coal-tar pitch (28 G) that contained 14 per cent of this inert, finely 
divided carbon made a satisfactory briquet with Illinois No. 4 coal 
when 6 per cent of the pitch was used, yet another coal-tar pitch 
(28 I) containing 37 per cent of the inert carbon failed to make a 
satisfactory briquet with the same coal when 14 per cent of the pitch 
was used. On the market the pitches sell at approximately the same 
price. The serious mistake made in crushing coal slack too fine is 
apparent. 

Fine crushing of the coal slack gives the briquet a smoother sur- 
face that is more resistant to the weather; but this increase in the 
quality of the briquet is usyally obtained at too great a cost, owing 
to the additional binder required, as explained above. Fine crushing 
also makes the briquet somewhat harder to ignite. 

Capillary pores increase the amount of surface to be coated and the 
amount of void space to be filled, and this is probably another reason 
why lignites require more binder than hard coals. 

It is interesting, in this connection, to note that with all binders 
the coherence in the briquets at first increases but slowly with increase 
in the proportion of binder. Then suddenly the coherence increases 
very rapidly and the briquets become strong. Then when an excess 
of binder is added the increase in strength is again only slight. The 
curve takes the form indicated in the accompanying diagram (fig. 1). 
The explanation, of course, lies in the fact that at first there is not 
enough binder to coat all the grains of coal and there can be little 
coherence. When sufficient binder has been added to coat the grains, 
the strength increases rapidly. After the grains have been well 





a Cassier’s Magazine, vol. 11, 1896, p. 23. 


CONDITIONS GOVERNING THE USE OF BINDERS. 19 


coated there is little further gain in strength with the use of additional 
binder. 


PERCENTAGE OF VOIDS. 


The amount of binder will depend on the amount of void space to 
be filled. There should always be enough of the finer coal and coal 
dust present to fill the spaces between the larger grains, or binder 
will be required to fill these spaces. Thus Wagner also found that a 
very large amount of binder was required to bind coal slack of a 
uniform size, five-sixteenths to three-eighths inch indiameter. Clifford 
Richardson, in a recent book on ‘‘ Modern asphalt pavements,” gives 
a calculation by Dr. G. F. Becker, of the United States Geological 


sa 


3 S 7 
Percentage of binder 


100) 






Coherence of briquet 


Fig. 1.—Curve showing relation between percentage of binder (water-gas tar pitch) and coherence of 
briquet. Other binders show similar curves, but with different percentages. 


Survey, as to the amount of void space. This calculation is in 
outline as follows: | 

Consider four spheres in a plane so arranged that the lines joining 
their centers form a square, and four other spheres above them. A 
cube is formed by the lines joining the centers of the eight spheres. 
If r is the radius of a sphere, then the volume of the cube is 8 r* and 
the void space is 8 r?>—4 z r*, and the percentage of void space is 
Sr—t ars 7 ; 
ees tg] 0-4764. If the spheres are placed obliquely, 
then the area of the parallelogram joining their centers is 2 7° V3, and 
multiplying this by the height of a tetrahedron formed by the 
centers of four spheres when three are placed in contact in one plane 


20 BINDERS FOR COAL BRIQUETS. 


and the fourth is placed on them, we have for the volume of the 





prism 4 V2 73. Then for the percentage of voids we will have 
4sVor—tar 7 
= =1- Vy = 9-2595. 
4%or 3¥ 2 


From these results it will be seen that the amount of void space 
between grains of uniform size is independent of the size of the grains. 
In practice, however, even shot will not pack quite so closely as the 
theory indicates, as is shown by the experiments of Richardson, who 
found that with shot the percentage of void space was about 32.¢ 

With grains of sand of uniform size but of irregular shape Richardson 
found the void space to average 43.6 per cent. It may be said, 
therefore, that in briquetting coal, 56.4 per cent of the total weight 
of the slack should be in grains about one-fourth inch in diameter. 

It is interesting to obtain some idea of the desirable fineness of the 
remaining coal particles. Without giving the calculation in detail 
we may say that theoretically the spheres fitting in the spaces between 
the larger spheres, and the yet smaller spheres fitting into the void 
places then left can be calculated. The calculation shows that if r 
represents the radius of the large sphere there would be for every 
large sphere one smaller sphere having a radius of .4142 r, two spheres 
having a radius .2247 r, five spheres having a radius .1763 r, and 
eight spheres having a radius .1543 r. The volume occupied by these 
smaller spheres will be 11.14 per cent of the total volume, and since 
the large spheres occupy 74.05 per cent of the total volume, we 
would have about 15 per cent of void space to be filled in by yet 
smaller spheres. With irregular grains the results would not follow 
the theoretical percentages; but in a general way it is apparent that 
although it is advantageous to have a large percentage of the grains 
coarse (say 60 per cent of 4-inch diameter), yet a considerable 
amount (say 40 per cent passing a 20-mesh sieve) of the finer slack 
and dust must be present to fill the voids. 

The coal used in briquetting being already for the most part fine 
slack, the best practical results will be obtained by not breaking any 
of the lumps that are larger than one-fourth inch in diameter more 
than is necessary to bring them to that diameter and by not crushing 
the finer coal at all. 


THICKNESS OF COATING. 
® 


The amount of binder necessary will depend on the thickness of the 
coat of binder over the surface of the grains of coal. The thickness 
of the coat of binder required will vary both with the coal and the 











a Thisis partly accounted for by the fact that the discussion of Doctor Becker does not consider the 
contact of the spheres with the walls of the container.—J. E. M. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 21 


binder, but principally with the binder. In general, it may be said 
that the binder should be dissolved or heated until it is in the condi- 
tion of a thin liquid capable of wetting the grains, somewhat as water 
would. With the harder pitches or asphalts, and similar binders, 
superheated steam for the mixers is a matter of necessity for economical 
working, for otherwise the binder does not become sufficiently liquid 
to spread in a thin coat and is therefore wasted. 


OTHER CONSIDERATIONS. 


The amount of binder required will depend to a slight extent on 
that portion of the coal which, being soluble in carbon disulphide, 
may be regarded as ‘‘bitumen”’ and as having some binding power. 
Constam and Rougeot? never found the amount of carbon disulphide 
extract to exceed 0.7 per cent, and probably with most coals the 
amount is negligible. 

If the coals are arranged in a series according to the percentage of 
one binder required they will retain that same order in the series 
when other binders are used. Furthermore, if the equivalent per- 
centages of different binders are determined for one coal then these 
equivalent percentages can be used for all coals, slight modifications 
only being sometimes necessary. An advantageous arrangement 
would be to place coals as ordinates and binders as abscissas in a 
table, and then the percentages of any binder required with any coal 
could be read directly. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 
METHODS AND SCOPE OF THE EXAMINATION. 


DETERMINATION OF PERCENTAGE OF BINDER. 


In order to determine in the laboratory the percentage of pitch 
necessary to briquet a given coal, 20 grams of coal, unless otherwise 
stated in the detailed report, was weighed out, mixed with the chosen 
percentage of binder, and placed in a Battersea crucible. A small 
amount of water was then added and the mixture heated, with suffi- 
cient stirring to mix the binder and coal thoroughly, until steam came 
off freely and only a small amount of water was left in the coal. The 
mixture while still hot was pressed in a small laboratory hand press, 
on which a pressure of 3,500 to 4,000 pounds per square inch was 
usually obtained. Each briquet made weighed about 5 grams, and 
thus four briquets were obtained as representing the test. The per- 
centage of binder was varied in subsequent tests until the correct 
percentage to produce a satisfactory briquet was determined. 

The percentage of binder was always calculated on the weight of 
the coal, consequently the percentage calculated on the weight of the 





a Zeitschr. f. angew. Chemie, vol. 17, No. 26, p. 1. 


Bo BINDERS FOR COAL BRIQUETS. 


briquet produced would be somewhat less. This is a matter of no 
consequence, however, as the method of grading the briquet was 
purely relative. 


DETERMINATION OF COHERENCE, 


The examination of the small briquets produced was somewhat 
crude—their coherence being determined by the way in which they 
crushed or broke. The briquets were graded by numbers as follows: 


1. Very slight coherence. 43. Excellent briquet; would stand rough 
2. Slight coherence. handling. 

3. Coherent, but not satisfactory. 5. A briquet stronger than necessary. 

4, Satisfactory. 


It was found somewhat difficult to compare extremely hard and 
brittle briquets with others not brittle but too soft. In all tests the 
intention was to produce a relative grading in which 4 would repre- 
sent a satisfactory briquet for ordinary use. In actual work the 
coherence of the briquet could be varied to suit the demand of the 
customer, but in no case probably would such variation exceed the 
range represented by the numbers 34 to 44. 


LIST OF MATERIALS STUDIED. 


The materials used to bind the particles of coal together may be 
either organic or inorganic, and a very large number of substances 
have at various times been suggested and used for this purpose. 

A list of the binders which have been examined is given below. 
An effort has been made to include in this list all binders which it 
was thought might be used commercially in the United States, as well 
as certain other substances which seemed fitted to throw light on the 
laws governing the action of the binder. Attempt was made to study 
such modifications and combinations of the different binders as it 
seemed might produce more efficient commercial results. For these 
latter modifications and combinations reference must be had to the 
detailed report. 


INORGANIC BINDERS. 


(1) Clay, (2) lime, (3) magnesia, (4) magnesia cement (magnesium oxide and mag- 
nesium chloride), (5) plaster of Paris, (6) Portland cement, (7) natural cement, (8) 
slag cement, (9) water glass. 


ORGANIC BINDERS. 


Wood products.—(10) Rosin, (11) pitch (rosin and tar), (12) pine-wood tar, *(13) 
hard-wood tar, (14) Douglas fir tar, (15) wood pulp, (16) sulphite liquor (from paper 
mills). ; 

Sugar-factory residues.—(17) Beet pulp, (18) lime cake, (19) beet-sugar molasses, (20) 
cane-sugar molasses. 

Starch.—(21) Corn starch, (22) potato starch. 

Slaughter-house refuse. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 98 


Tars and pitches from coal.—(23) Blast-furnace tar, (24) producer-gas tar, (25) illu- 
minating-gas tar, (26) by-product coke-oven tar, (27) coal-tar creosote, (28) various 
grades of pitches from various tars. 

Natural asphalts.—(30) Impsonite, (31) gilsonite, (832) maltha, (33) refined Trinidad, 
(34) refined Bermudez, (35) hard and refined asphalts (from ae Sse sandstones, 
etc.). 

Petroleum products.—(36) Crude oil, (37) residuum (asphalts, etc.), (38) water-gas 
tar, (39) water-gas tar pitch, (40) wax tailings, (41) acid sludge, (42) ears tar; (43) 
Pintsch gas tar, (44) Pittsburg flux. 


INORGANIC BINDERS. 


GENERAL STATEMENT. 


The great disadvantage of inorganic binders is that they all add 
ash to the fuel. This means freight on just so much noncombustible 
material, less heat return for a given weight of fuel consumed, and an 
added amount of ash on the grate. All briquets made with inor- 
ganic binders are weak when first pressed and strengthen only grad- 
ually. Inorganic binders possess the advantage that they are not 
volatile, and hence the briquets, even when made from a noncaking 
coal or lignite, will stand up well in the fire without disintegration. 
They also have a tendency to lessen the smoke produced. ‘This is 
due to the fact that the binder enables a somewhat slower and more 
complete combustion to take place and does not itself contribute any 
smoke to the fuel. 

Another slight advantage sometimes reed for certain of the 
inorganic binders, such as lime, water glass, and magnesia, results 
from the tendency of the calcium, sodium, and magnesium to combine 
with the sulphur, thus diminishing the escape of the sometimes objec- 
tionable oxidation products of that substance. This action would 
be the same if the calcium, etc., existed in the binder in chemical com- 
bination, as it occurs in calcium resinate. (See ‘‘ Rosin,” p. 30.) 
For the purpose of testing the above-mentioned claim, a briquet 
was made with Indiana No. 8°coal and 4 per cent of magnesium 
oxide. The briquet was dried and then burned. The sulphur in the 
ash (determined by the kindness of Mr. Somermeier) was found to 
amount to 0.44 per cent. As the sulphur in the coal was 3.72 per 
cent, it is evident that only a small fraction of the sulphur is retained by 
the magnesium oxide used asa binder. The same would probably also 
hold true for calcium and sodium compounds. It is thought, there- 
fore, that the advantage thus gained is not great enough to merit 
consideration in practice. 

Evidently the disadvantage resulting from the addition of any 
large percentage of an inorganic binder is too great to justify its use 
except as a matter of great saving in cost, or as a matter of necessity, 
in order to hold together in the fire some entirely noncaking coal and 
produce a low grade of fuel therefrom. 


24 BINDERS FOR COAL BRIQUETS. 


The essential results of the tests made with the different coals and 
binders are assembled in the table at the end of this report, wherein 
is shown the percentage of binder necessary to produce a satisfactory 
briquet with the coal considered. 

The work of the laboratory can be regarded as sufficient so far as 
the negative results are concerned, but in all cases where the labora- 
tory work seemed to promise commercial results the experiments 
should be repeated on a larger scale. 

The inorganic substances which were tested are the only inorganic 
materials whose use as a binder on a commercial scale seemed even 
so remotely possible as to warrant testing in the laboratory. A list 
of other inorganic substances which have been suggested as binders, 
or as possible constituents of binders, would include chalk, alum, 
ammonium chloride (sal ammoniac), copper sulphate, sodium hydrox- 
ide, sulphur, potassium nitrate, calcium chloride, etc. That all these 
substances are totally unfit for such purpose appears at once from a 
knowledge of their properties, and they were not considered further. 


DETAILED DESCRIPTION. 


1. Clay.—The tests shown in the table (pp. 51-52) were made with 
a good sample of potter’s clay obtained through Dr. J. H. Pratt. Clay 
is cheaper than coal and its cost, considered as a binder, is therefore 
a minus quantity. 

The briquets when first taken from the press were extremely weak, 
many of them breaking while being taken out. The full pressure 
could not be given, for the coal would crush through the narrow, 
practically closed space between the molds and the bed plate. After 
drying, the briquets were hard and rather brittle. In water. they fell 
to pieces completely and quickly. In the fire they hardened and 
stood up well, except those made of the noncaking lignite, California 
No. 1, which nevertheless stood up far better than with most binders 
and in comparison with the usual behavior of this lignite could be 
called very satisfactory. 

Clay was used as a binder at one of the first plants established in 
this country, the Loiseau plant at Port Richmond, Pa. Trouble was 
experienced with the press used, the briquets when first made show- 
ing weakness. This was finally overcome, but the binder was aban- 
doned owing to the expense of drying and waterproofing the product. 
Briquets made at this plant with clay were said to be very satisfactory 
in the fire. 

Any press using clay for a binder would probably have to be 
specially adjusted. Owing to the large addition of ash, and to the 
expense of drying and waterproofing the briquet, it is improbable 
that clay will ever prove advantageous as a binder. If used alone it 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 25 


can only be for the manufacture of a poor grade of fuel, incapable of 
standing any exposure to rain. 

Clay in connection with other binders may be regarded as an 
adulteration of very doubtful value to the consumer. 

2. Iame.—Lime, or rather, milk of lime, Ca(OH),, has often been 
suggested as a binder, and is said to have been used. The tests 
shown in the table were made with calcium oxide known to be chem- 
ically pure. In these tests the lime was mixed dry with the coal, and 
then water was added. In some of the tests an excess of water was 
added and later boiled off; in others an excess of water was added 
and then squeezed out in the press; and in yet others only sufficient 
water was added to thoroughly moisten the mass. After drying, all 
the briquets were very weak, those in which the largest percentage of 
calcium oxide was used being the worst. They finally disintegrated, 
merely from exposure to the air. 

From these tests it is difficult to understand how it is possible to 
use lime alone to make a briquet. For further experiments with 
lime see ‘‘ Rosin,’’ (p. 30). 

3. Magnesia.—The sample of magnesia tested was a light, calcined 
magnesium oxide. In the tests shown in the table (pp. 51-52) the 
magnesium oxide was mixed with the coal and then a sufficient amount 
of water was added. In some tests the briquet was pressed cold 
and in others more or less of the water was evaporated. The results 
show that 3 to 5 per cent of this binder would make a satisfactory 
briquet, except with certain lignites. The briquets are very hard 
and would stand heavy pressure, but are brittle if less than 4 per cent 
of binder is used. “In water the briquets go to pieces, though far less 
rapidly than those made with clay. In the fire they behaved very 
well, some being satisfactory even when only 2 per cent of binder was 
used. 

In the United States magnesite, from which magnesia is obtained, 
is found only in California, where the production of magnesium oxide 
in recent years has been as follows: 


Quantity and value of magnesia produced in the United States, 1901-1906. 
































, Val ; 7 Val 
Year. Quantity. per bert z ears Quantity. Syston a 
Short tons. Short tons. 
Le 1,666 Mie OON I ADOS Med. bene. hoe oa MOG OR 1,357 $8. 22 
oo She aaa Gul oe ll a 1,349 FE Tt Eorpap epi ASP aan SR ed 1, 873 9. 76 
OT | 1,750 Peerless. Soar IE. oe Fe 3,714 7. 56 





a Based on value of raw magnesite, with 10 percent added to covercost of manufacture of magnesium 
oxide therefrom, being a suggestive approximation only. 


The production could be greatly increased, several million tons of 
the magnesite being now in sight. The mineral is calcined for the 


26 BINDERS FOR COAL BRIQUETS. 


production of carbon dioxide, leaving the magnesia, which is used 
principally for covering steam and heating pipes, by paper mills, 
and in the manufacture of bricks for lining open-hearth furnaces and 
converters. 

At the price prevailing in 1903, the cost of 3 per cent of this binder 
would be about 22 cents per ton of briquets produced. Three or four 
per cent of ash added to the fuel would not be greatly injurious, and 
the binder would possess an advantage over organic binders in hold- 
ing the briquet together in the fire and in reducing the smoke. 

The claim that the magnesia in the briquet reduces the amount of 
sulphur that escapes from the coal, as already pointed out (p. 28), 
seems to be of no practical importance. 

It seemed possible that coke breeze might be briquetted with this 
binder, the briquets to be used in the place of coke in the furnace. 
Laboratory experiments on this point, however, gave unsatisfactory 
results, as follows: 


Results of briquetting coke breeze with magnesia. 


Percent-| Grade 
age of | of coher- 
binder. ence. @ 





a See p. 22. 


In water the briquet with 6 per cent of magnesia behaved fairly 
well and that with 8 per cent splendidly, but in the fire the briquet 
with 4 per cent was unsatisfactory, that with 6 per cent was only 
fair, and that with 8 per cent was very hard to ignite. 

For results of experiments with mixtures of magnesia and organic 
binders see p. 49. 

4. Magnesia cement.—In .1880 Dr. A. Gurlt recommended a binding 
material consisting of 30 parts of 45 per cent magnesium chloride, 
30 parts of 93 per cent magnesium oxide, and 60 parts of water. He 
used 5 per cent of this material and says that it produced a stronger 
briquet than any other and that it adds only 2.5 per cent of ash. The 
statement as to the amount of ash (magnesium oxide) added is cor- 
rect. The formula on examination, leaving out the water, is found 
to reduce to 5MgO.MegCl,. The evidence on which this formula was 
taken as the most advantageous for the cement is not stated. The - 
results reported in the following table are based on the proportions 
shown for the formulas therein given: 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 27 


Results of briquetting Illinois No. 11 B coal with varying formulas of binder. 








Calculated for 2 per cent | Calculated for 3 per cent 
of magnesium oxide in of magnesium oxide in 





the ash. the ash. 
Formula. Amount of binder Amount of binder Remarks. 
per gram of coal. bi ie per gram of coal. ab ins 
ina ld 2 Nn atl a sl of co- 





Gram. Gram. Gram. Gram. 

MgO MeCls >» ey 0.0100 | 0.0500 231 0.0150 | 0.0750 3 

gO.MgCle......... .0133 . 0334 23} — .0200 . 0500 3 
3MgO.MgCly.......... "0150 |  .0250 2%} :0225|  .0375 3 |\Stronger than preced- 
4MgO.MgClo......... . 0160 . 0200 23} 0240 . 0300 Sipe tHe: 
5MgO.MgCle......- a tees 0107 . 0167 3 0250 . 0250 3} 
6MgO.MgCle......... .0171 .0145 3 0256 . 0216 34||Apparently of about 
7MgO.MgCls........- 0175 .0127 3 0262 0190 33|( equal strength. 
TT a PTO eee . 0200 . 0000 3 0300 0000 34 





@ Bituminous coal (one-half run of mine, one-halflump) from shaft near Carterville, Williamson 
County, Ill. For description, analysis, and tests see Bull. U. S. Geol. Survey No. 290, 1906. 
+See explanation under '* Determination of coherence”’ (p. 22). 


In these tests the magnesium oxide was mixed dry with the coal, 
and then the magnesium chloride (dissolved in water) was added. 
As already stated, the method of testing the small briquets made 
does not allow of minute differences being noted, but the results 
showed clearly an increase of strength until the proportion given 
by Doctor Gurlt and represented by the formula 5MgO.MeCl, was 
reached. On still further decreasing the proportion of the magne- 
sium chloride the briquets apparently did not grow either weaker or 
stronger. Magnesium oxide is cheaper than the chloride, and in view 
of the results obtained there is considerable doubt as to the advan- 
tage of adding the chloride. The addition of the chloride is said to 
make a more quickly setting cement, and one that is more insoluble, 
owing to the formation of an oxychloride of magnesium, but the 
statement is not verified. The magnesium chloride would also have 
the disadvantage of losing its chlorine in the fire, and this might 
come off either free or combined with hydrogen as hydrochloric 
(muriatic) acid. In either case the resulting gas is exceedingly cor- 
rosive and would greatly injure the boiler flues. Possibly all of the 
chlorine would be retained by the coal ashes, but it is a matter of grave 
doubt. 

In the fire briquets made with 3 per cent of magnesia cement of 
the formula 5MgO.MeCl,—that is, 3 per cent after calculating the 
formula to MgO—stood up well. In water they disintegrated after 
some time. It was not evident that the briquets with magnesia 
cement of this formula behaved any better in water than briquets 
made with the same ash percentage of magnesium oxide alone, if 
indeed they behaved so well. 

Magnesium chloride is ordinarily sold in the market in the crystal- 
lized form MgCl,.6H,O. This grade is quoted at $20 per ton in large 
lots in New York. It is not produced to any considerable extent in 
this country, but should the demand arise could probably be made 
from the California magnesite without increasing the cost. 


28 BINDERS FOR COAL BRIQUETS. 


All the briquets made with the magnesia cement were very hard but 
very brittle. They would stand great pressure, but apparently 
would not stand rough handling, when only 5 per cent of the cement 
is used, as recommended by Doctor Gurlt. 

5. Plaster of Parvs.—Gypsum, the mineral from which plaster of 
Paris is produced, is widely distributed in the United States. In 
1903 the production was 264,196 tons, valued at $4.08 per ton. 

The tests shown in the table (p. 51) were made with plaster of 
Paris which was first mixed with the coal. Sufficient water was 
added to thoroughly moisten the mass, and then pressure was applied, 
the excess of water, if any, running out in the press. The briquets 
were very hard, but also brittle, and would not stand rough handling 
unless at least 12 per cent of binder was used. Even these were not 
first-class briquets. In the fire the briquet with 12 per cent of 
binder held together perfectly, and would have held together with a 
smaller percentage. In water the briquet went to pieces more 
rapidly than was expected. 

Although even 12 per cent of plaster of Paris in a briquet would 
not be prohibitive as regards cost (50 cents per ton of briquets pro- 
duced), it would be as regards the addition of ash, and would more- 
over cause a much slower combustion of the briquet. A briquet 
with 6 per cent shows considerable coherence and might be satis- 
factory for some purposes. For results of experiments with mixtures 
of plaster of Paris and organic binders see page 49. 

6. Portland cement.—In 1903, 22,342,973 barrels of Portland 
cement, weighing 400 pounds gross each, were produced in the United 
States. The average value per barrel was $1.24, and allowing 20 
pounds tare for the barrel, the value per ton was $6.52. 

The sample of Portland cement tested was obtained from Mr. 
Richard L. Humphrey and was a mixture of seven well-known 
brands, constituting what has been termed typical cement. In the 
first. tests made the cement was mixed with the coal, then an excess 
of water was added and largely boiled off, after which the coal was 
pressed. The results not being satisfactory, in subsequent tests less 
water was added and the mixture was not heated, but the results 
were only a little better. In the fire briquets with 12 per cent of 
binder held together well, and a smaller percentage would have been 
sufficient. In water the briquets went to pieces somewhat more 
rapidly than those made with plaster of Paris. 

This binder is more expensive and certainly no better than alastar 
of Paris. For results of experiments with mixtures of Portland 
cement and organic binders see page 49. 

7. Natural cement.—In 1903 the production of natural cement in 
the United States was 7,030,271 barrels, of 300 pounds gross weight 
each. The average value was $0.522 per barrel, equivalent to $3.73 
per ton, allowing 20 pounds tare for the barrel. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 29 


The tests were made with a sample from Louisville, Ky., which 
was mixed dry with the coal and then sufficient water was added 
before pressing. The results were very nearly the same as with 
Portland cement, the briquets being hard and brittle. In the fire 
the briquets held together excellently, but in water they would not 
stand up particularly well. Natural cement would make a cheap 
binder but would have to be used in such large quantity as to be 
very objectionable. 

8. Slag cement.—In 1903, 525,896 barrels of slag cement, of 380 
pounds net weight each, worth $1.03 per barrel, equivalent to $3.42 
per ton, were manufactured in the United States. Tests were made 
with slag cement as with the other cements, the results indicating 
its inferiority to either the Portland or the natural cement as a 
binder for coal slack. 

9. Water glass.—Water glass, or sodium silicate, is produced to a 
considerable extent in the United States, 32,651 tons having been 
manufactured in 1900, with an average value of $12.74 per ton. 

It is said that this material will make coherent briquets when 0.75 
to 1 per cent is used. Two different samples were tested. The 
requisite amount was dissolved in hot water and mixed with the coal, 
any large excess of water was boiled off, and then the briquets were 
pressed. The results were unsatisfactory even when 12 per cent of 
binder was used. The experiments were then repeated with less 
water and no heat, but the results obtained were no more satisfactory. 
When the sodium silicate was analyzed one sample was found to con- 
tain only 86 per cent of the requisite amount of silica and 13.4 per 
cent of the requisite amount of sodium required by the formula for 
the normal silicate (Na,SiO,). The other sample, which behaved 
only a little better, showed on analysis 11.1 per cent of Na,O and 
27.4 per cent of SiO,. These poor analyses may account to some 
extent for the lack of success obtained with the water glass, but the 
results are apparently sufficient to show that it is not suitable for use 
as a commercial binder. 


ORGANIC BINDERS. 
WOOD PRODUCTS. 


10. Rosin.—In 1900, 300,000 tons of rosin, valued at $17.02 per 
ton, were produced in the United States. Of this amount, according 
to the Census report, only 7.6 per cent was used for domestic con- 
sumption. In 1905 the price of rosin, for even the lower grades, A 
to C, had risen to $29 per ton. 

Rosin consists mainly of abietic acid or similar isomeric acids or 
anhydrides. The formula of this acid is given as approximately 
C,,H,,O,, and its acid equivalent as 145 to 185. This means that if 
calcium oxide is used to neutralize the acid 0.0725 to 0.0925 gram 
should be added to 1 gram of the rosin to form calcium resinate. 


30 BINDERS FOR COAL BRIQUETS. 


The density of rosin ranges from about 1.07 to 1.08. Rosin softens 
at 80° C. and melts to a limpid liquid at 100° C. The melting point 
of abietic acid is stated to be 165° C. Rosin is entirely soluble in 
carbon disulphide. 

The sample of rosin tested melted at 100° C. The tests made are 
shown in the table (pp. 51-52). The briquets withstood exposure to 
the weather well and, except those made with lignites, were satisfac- 
tory in the fire, though inclined to smoke. 

An attempt was made to see if the addition of lime would improve 
the binding qualities of the rosin. Three grams of rosin mixed with 
0.25 gram of lime melts to a thicker mass, more brittle than the rosin 
alone. If the amount of lime is increased to 0.50 gram the brittle- 
ness is very much increased. Experiments made on Illinois No. 6 B 
coal, with varying proportions of lime and rosin, gave the following 
results: 


Results of briquetting Illinois No. 6 B coal@ with varying proportions of rosin and lime. 








Percentage of rosin used. 

















2 4 6. 8 
First series: 
Neimieraddead Shiels eked sew a eae Oe eee re ems gram..| 0.033 | 0.067 0.1 | 0.183 
CITA OL CONCTENCE Oo) iso oc na sc nee oa oh coke olketuny Hise enn 2 3 33 34 
Second series: 
MUTT AIO She of oe an ce aida ois ca Ac ee ene oo ate ee ee Rp gram..| 0.066; 0.134 0.2 | 0.266 
ane GLeoheronce yes 00. ae NTs el Oe en ee 2 2% 3 3 

















a Bituminous coal from Coffeen, Montgomery County. For description, analysis, and tests see 
sige Lefe e feo Survey No. 290, 1906. 
ee p. 2 


As 20 grams of coal were used the lime added in the first series was 
just sufficient to react with the rosin. The increase of lime appears 
from the above results to be detrimental, and the experiments were 
therefore not carried further. It appears that 6 per cent of rosin will 
be necessary to produce a satisfactory briquet with most coals, and 
inasmuch as rosin is now worth about $29 per ton its use as a binder 
is unprofitable. Nor is it likely that it will again become cheap 
enough to permit its use as a binder, either alone or in combination 
with other materials, such as tar. 

11. Pitch.—Owing to fluctuations in the price of rosin, pitch, which 
is a mixture of rosin and tar, is variable in cost. In 1905 a good 
grade of navy pitch was quoted at about $35 per ton in St. Louis. 
The sample of pitch tested was of this grade. For the results of the 
tests made see table on pages 51-52. 

Only 3 or 4 per cent of this pitch is necessary to produce a satis- 
factory briquet. The briquets stood the weather well and, except 
those made with the lignites, proved satisfactory in the fire. 

The improvement of rosin as a binder by the addition of tar might 
have been predicted from the principles laid down, for rosin alone is 
too brittle to produce a tough briquet with a low percentage of binder, 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. oF 


and thinning the rosin with a heavy oil, such as tar, thus making it 
less brittle, would doubtless be advantageous. However, even where 
only 3 per cent of pitch is necessary to produce a satisfactory briquet 
its cost will probably always forbid its use. 

12. Pine-wood tar.—No accurate data as to the amount of tar pro- 
duced in the United States could be obtained. The census of 1900 
reported 84 wood-distillation plants, but these were mostly using 
hard woods. The tar produced should be from 4 to 10 per cent of 
the weight of the hard wood used, but no record of the output was 
made, the tar being mainly burned under the retorts. The number 
of distillation plants in the South using pine wood has been consider- 
ably increased since the census of 1900, and plants have also been 
erected to use fir in the northwest. Both pine and fir yield much 
larger percentages of tar than the hard woods, and it may be that in 
the future the tar obtainable from these sources will be available for 
briquetting plants in neighboring sections of the country. The cen- 
sus for 1900 showed exports of 36,535 barrels of tar and pitch, valued 
at $77,082, or $15 per ton. Pine tar is quoted at 6 to 10 cents per 
gallon, equivalent to $13.80 to $23 per ton. 

In the distillation of wood various grades of oils and tars are pro- 
duced, depending both on the wood used and on the manner of dis- 
tillation. An examination of representative samples of these various 
grades was undertaken in order to determine their value for briquet- 
ting purposes and also to determine how the product could best be 
made suitable for such purposes. 

A solid pine-tar residuum, obtained from Summerville, S. C., was 
designated 12 A. The final results of the tests made with this binder 
areshown in the table (pp. 51-52). All the briquets except those made 
of lignite behaved satisfactorily in the fire. The pitch softened at 80° 
to 90° C. to a very sticky mass that apparently should bind well, but 
some of the briquets, even with 10 and 12 per cent of the binder, were 
too brittle, although they were sufficiently hard. The poor results 
with this binder were attributed to the high percentage of carbon in 
the pitch and to the failure of the pitch to spread well over the grains 
of coal. The pitch dissolved readily in either wood-tar creosote or 
coal-tar creosote. The following tests were made: 


Results of briquetting Arkansas and Illinois coals with varying proportions of pine- 
fl wood tar and creosote oil. 


Binder (per cent). 


Grade of 


Coal. Wood Coal-tar 





Pine-wood coherence.a 

tar 12 A. ie ERS 
eR OR ee es age { 4 vy Ls Linch tas Ne 7 4 
~shaset 6 ie aes ee 4 
OVE TONGS TES, A A a ea A 6 3 4 


a See p. 22. 


32 BINDERS FOR COAL BRIQUETS. 


As was to be expected, these briquets smoke, but they stand up 
satisfactorily in the fire. The experiments show the improvement 
which may be made by thinning a pitch to the proper consistency. 
This holds also for coal-tar pitches, as will be seen later. 

The pitch here discussed is a waste product, but being produced 
at only a few plants is not available in quantity. 

A sample of very thick pine-wood tar, obtained from Cheraw, S. C., 
was designated 12 B. Its flowing point was 45° C. and only 3 per 
cent was volatile below 270° C., the volatile portion being mostly 
water. This tar had a density of 1.07. The results of the experi- 
ments made with it are summarized in the table (pp. 51-52). 

The briquets produced some smoke, but were satisfactory in the 
fire except when made with lignite. They stood the weather well. 
This tar may prove an available binder for some briquet plants. It 
is obtainable at many wood-distillation plants at prices ranging 
from $15 to $20 per ton, and as only 3 to 4 per cent is necessary to 
produce a satisfactory briquet with most coals the binder would 
range in price from 45 to-80 cents per ton of briquets produced. 

Another sample, of a slightly more mobile tar than 12 B, obtained 
from the same plant, was designated 12 C. Its flowing point was 
42° C. and its density 1.05. About 14 per cent of this tar distilled 
below 270° C. The results of the experiments with it are given in the 
table (pp. 51-52). This tar is obtainable from any of the wood-dis- 
tillation plants that could furnish tar like the sample 12 B, and would 
command about the same price. It contains a little more of the 
low-boiling oils—that is, those distilling below 270° C.—than sample 
12 B, and requires about 1 per cent more of the tar to produce a 
satisfactory briquet. 

A sample of pine tar obtained at St. Louis, Mo., was designated 
12 D. It was liquid at 20° C. and had a density of 1.14. On distil- 
lation about 10 per cent came off below 200° C. and 25 per cent below 
270° C. The following experiments were tried: 


Results of briquetting Illinois No. 6 B coal with binder 12 D. 





‘Peroentage Grade of 
of binder. | coherence.a 





— 

NOD PND 

we WWW CO 
eo 


a See p. 22. 


The tar was evidently too liquid to produce satisfactory briquets. 
The residue left after distillation at 270° C. was then tested and 
gave a satisfactory briquet with Illinois No. 6 B coal when only 4 
per cent of binder was used. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 33 


Another sample of pine-wood tar, obtained from a wood-distilla- 
tion plant at Dunbar, 8. C., was designated 12 E. It was found that 
about 5 per cent of this tar would produce a satisfactory briquet 
with Illinois No. 6 B coal. 

Another sample of pine-wood creosote, obtained from Cheraw, 
S. C., was designated 12 F. This sample was liquid at 20° C. and 
had a density of 1.12. On distillation about 20 per cent by volume 
came off below 112° C., the distillate being mostly water, and 21 per 
cent more came off below 270° C. At 310° C. the residue swelled 
up and frothed over. The briquets made with this binder were not 
satisfactory, the reason being that the creosote was so thin that the 
briquets were easily crushed. They smoked in the fire, gave off the 
odor of creosote, and did not stand up well. The residuum left after 
the distillation of the creosote had been carried to 270° C. was tested 
with Illinois No. 6 B coal, the coherence being 3 and 4 with 6 and 8 
per cent of binder, respectively. 

A sample of pine-wood creosote, obtained from a plant at Dun- 
bar, S. C., designated 12 G, was not tested, being similar to 12 F, 
with which no satisfactory results could be obtained. Another 
sample of turpentine oil obtained from the same plant, designated 
12 H, was evidently of no value for briquetting purposes. 

13. Hard-wood tar.—The sample of hard-wood tar examined was 
a rather thin liquid even at the ordinary temperature, and could not 
therefore make a sufficiently hard briquet. It had a density of 1.10. 
The following tests were made: 


Results of briquetting Illinois No. 6 B coal with hard-wood tar. 





Percent- | Grade of 
age of coher- 
binder. ence.@ 








NOD Pb 
Ww OO bo bh 


— 
wi 





a See p. 22. 


On distillation below 112° C. the tar gave off 8 per cent of water; 
from 112° to 270° C. it yielded 44 per cent more of a light oil and of 
reddish paraffin oils. On testing the residue a satisfactory briquet 
was obtained with Illinois No. 6 B coal when 8 per cent was used as 
a binder. It is concluded, therefore, that the residue left from hard- 
wood tar after distillation to 270° C., where it is obtainable, could 
be used advantageously for briquetting. 

14. Fir tar—The sample of fir tar tested was obtained from a 
wood-distillation plant in the State of Washington. On distillation 
the tar gave off 8 per cent below 270° C. The results of the tests 


98315°—Bull. 24—11—3 


34 BINDERS FOR COAL BRIQUETS. 


are shown in the table (p. 51). As will be seen, the tar produces 
satisfactory briquets when 6 per cent is used. 

Concerning the use of wood tar in general for briquetting, the con- 
clusions to be drawn are that the distillation of the tar should in 
general be carried to 270° C., and the residue, which will be either a 
thick tar or a soft pitch, should be used. The briquetting qualities 
of a tar thus prepared will vary considerably with the source of the 
tar. Pine tar is best, about 4 per cent being required; fir tar comes 
next, about 6 per cent being required; and lastly, hard-wood tar, 
about 8 per cent being required to produce a satisfactory briquet. 
The work has not been extended to a sufficient number of samples 
of tar to make the above conclusions as regards the percentage of 
each tar required absolutely certam, but the percentages given will 
serve as the basis for a rough estimate of the cost of wood tar as a 
binder. In some localities this product might compete successfully 
with other binders. 

15. Wood pulp.—The claim has been made that cellulose, which is 
the main constituent of prepared wood pulp, has binding properties, 
but a few experiments point to the conclusion that its use is wholly 
impracticable. Possibly the term was confused with lignocellulose, 
the lignone groups affording the main constituents of the sulphite 
liquor discussed in the next section. 

16. Sulphite liquor.—In the manufacture of paper, wood pulp is 
treated with sulphurous acid to remove certain lignone groups, which 
combine with the SO,H and are then removed in the waste water, 
in which they are soluble. This waste liquor, amounting to ten or 
twelve times as much as the cellulose fiber produced, yields on 
evaporation an average of 9 to 10 per cent of solid residues. Roughly, 
therefore, the amount of this solid waste material is equal to the 
amount of cellulose obtained. According to the United States Census 
report for 1900 the amount of sulphite fiber produced was 416,037 
tons, and the estimate indicates that there was an equal production 
of the waste lignone complex. 

Not only is this liquor a true waste material, finding at present no 
market, but its production is a great nuisance, for it very seriously 
pollutes the streams on which the mills are situated and gives rise to 
much trouble. Its cost, therefore, would be represented solely by 
the cost of getting rid of the excess of water and by the freight to the 
briquetting plant. The water could be removed by evaporation, 
during which process the complex groups are to some extent broken 
down, sulphur and sulphur compounds being formed and some of 
them escaping. Of the solid residue left from evaporation 20 per 
cent is inorganic material and 80 per cent is organic. An ultimate 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 35 


analysis of the lignone complex groups shows, according to Cross and 
Bevan, carbon, 50.22 to 56.27 per cent; hydrogen, 5.22 to 5.87 per 
cent; sulphur, 5.52 to 8.80 per cent. 

Efforts have been made by various investigators to separate the 
liznone complex groups from the water by precipitation instead of by 
evaporation. It is possible that some process of settling and filtra- 
tion may recover the desired gummy residues without going to the 
expense of evaporating the water, but the processes so far devised 
are as yet unsuccessful on a commercial scale. 

The sample of sulphite liquor examined was obtained from Detroit, 
Mich. On evaporation it showed a dry residue of 11.8 per cent. 
This residue, of course, does not melt but chars and decomposes if 
heated to a high temperature. Before evaporating quite to dryness 
the residue is a very sticky, gummy mass, easily soluble again in water. 
The original liquor was evaporated to about one-third of its bulk and 
when in this condition was used in the following tests: 


Results of briquetting California lignite® and Illinois coal with sulphite liquor. 











Grade of 
Percent- coherence. ? 
feo! 
binder. | Califor- | Illinois 
nia No.1.| No. 6 B. 


Ne NR 


[=r] 
He u& Co CO BD OD 


iH 





a V.ignite from Tesla, Alameda County. For description, analysis, and tests see Bull. U.S. Geol. 
Survey No. 290, 1906 
b See p. 22. 

The briquets from Illinois No. 6 B coal, with 10 per cent binder, 
and from California No. 1, with either 10 or 12 per cent binder, were 
satisfactory in the fire. The briquets made from the California 
lignite show the good effect of using a binder which does not volatilize 
or melt, for this coal is one of the most difficult of all the coals with 
which to obtain satisfactory results in the fire. In water, of course, 
the briquets will go to pieces rapidly. 

It must be remembered that the above percentages of binder refer 
not to the dry residue from the sulphite liquor, but to the liquor 
itself when concentrated only to one-third of its bulk. To compare 
the results with the dry material the percentages must be divided 
_by three. In other words, we have from the paper mills each year 
1,200,000 tons of waste material which will produce coherent briquets 
when 10 to 12 per cent of it is used as a binder. The drawback to 
its use is the fact that the briquets are not waterproof, and a few 


36 BINDERS FOR COAL BRIQUETS. 


preliminary experiments were made in an endeavor to overcome 
this difficulty, with the following results: 


Results of briquetting California lignite and Illinois coal with varying proportions of 
sulphite liquor and other binders. 


Binder (per cent). 





























Spas, , 
Coal. Sul- Waterproofing constituent. ene poe ae 
phite i ence.@ 
liquor. Material. Amount. 
California No.1 (ignite).-..--{  §] odo. I) | 4 | OT) ara 
6 | Coal-tar creosote......- 4 3g] Qos 
TilingisiNo7G. 3 at ke ee. ae SricAspbalt tar. sees lee 4 4 | O, Keo} Bait 
Gl SPICCH 50 See. eee eee 4 4 | OF Keeee iar 








a See p. 22. 


These experiments indicate that oils and pitches mixed with the 
sulphite liquor will render the briquet more or less waterproof, 
depending on the extent and character of the added constituent. 
The whole problem is an important and promising one and deserves 
further investigation. 


SUGAR-FACTORY RESIDUES. 


17. Beet pulp.—sSeveral samples of beet pulp (a waste product) 
were examined and carefully tested in the hope that they might 
contain sufficient starchy or sugary material to serve as a binder. 
The results showed that the pulp could be of no use whatever for 
this purpose. Details of the tests need not therefore be given. 

18. Lime cake-—The sample of lime cake examined proved to be 
practically pure calcium carbonate, which could be of no possible 
use in briquetting. 

19 and 20. Beet-sugar molasses and cane-sugar molasses.—The 
binding power of molasses is said to be due to pectin, which is a 
body closely related to mucilage and has the constitution of a 
typical lignocellulose. To a less extent the binding power is due 
to sugar. Molasses contains only about 10 per cent of ash. From 
1 to 1.5 per cent of molasses in water is said to be sufficient for 
binding, but the experiments do not verify the statement. Three 
samples of beet-sugar molasses were examined—19 A, 19 B, and 
19 ©. Samples 20 A and 20 B were cane-sugar molasses. The 
moisture and ash were determined as follows: 


Moisture and ash in beet-sugar and cane-sugar molasses. 





Cane-sugar 


Beet-sugar samples. samples 


19 A. | 19B. | 190. | 20A. } 20B. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 37 


Tests in briquetting Illinois No. 6 B coal with these samples gave 
the following results: 


Results of briquetting Illinois No. 6 B coal with varying percentages of beet-sugar and 
cane-sugar molasses. 


Grade of coherence.a@ 


| 
Percentage | 
of binder. | 19 4. | 19B. | 190. 

















@ See p. 22. 


The coherence of the briquets did not seem to be increased by 
using more than 6 per cent of molasses. The failure to obtain good 
briquets with smaller percentages or to obtain satisfactory briquets 
even when the higher percentages were used is hard to explain. 
Heating the briquets to a higher temperature, even to 150° or 160° C., 
did not seem to improve them. Their behavior in the fire could not 
be regarded as very satisfactory. In water they fell to pieces. 

Some experiments were made with lime and molasses and also 
some attempts to waterproof these briquets, but no very satisfactory 
results were obtained. The use of molasses as a binder needs further 
investigation before it is finally classed as being of no use for briquet- 
ting, but so far it would seem to be without commercial value for 
this purpose. 

_ The census report for 1900 showed that there were 3,551,856 gallons 
of this molasses produced, valued at $25,102 for the portion sold. 
Much of it went to waste. 

STARCH. 


21. Cornstarch.—In the tests of cornstarch it was first necessary 
to determine if heating the starch with water to a paste, thus forming 
dextrin, before mixing it with the coal was essential, or if the change 
of starch into dextrin would take place as well when the starch was 
first mixed with the coal and the mixture then moistened and heated. 
The experiments showed that the latter procedure was fully as effect- 
ive. Starch was tested more particularly with the lignites, because 
it does not evaporate before burning, and hence would hold the lignite 
together in the fire. The results of the tests are shown in the table 
(pp. 51-52). In all the tests the behavior of the briquets in the fire 
was far more satisfactory than if pitch or a similar binder had been 
used. Starch possesses the advantage over such binders that it adds 
no smoke-producing material to the coal. 

In water these small starch briquets fell to pieces in a few minutes, 
and the next endeavor was to waterproof them. Many attempts were. 


88 BINDERS FOR COAL BRIQUETS. 


made to accomplish this end by immersion in oil. The experiments 
indicated that any oil would waterproof the briquet when externally 
applied, but asphalt tar, which was the thickest oil tested, gave the 
best results. It is doubtful if external waterproofing with a thick oil 
would ever be commercially successful, owing to the cost and diffi- 
culty of manipulation, but a thin oil, such as crude petroleum, might 
answer. At any rate, laboratory tests with small briquets can not 
finally decide the point, and the experiments should be conducted on 
a larger scale. 

An endeavor was also made to waterproof by mixing the coal and 
starch with some of the oils before briquetting. For this purpose 
Hoffman’s petroleum, Kansas crude oil, coal-tar creosote, asphalt 
tar, water-gas tar pitch, coal-tar pitch, and hard-wood tar were used 
under varying conditions and with varying percentages both of the 
starch and of the oils. The experiments indicate that the presence 
of crude oil or tarry liquids is detrimental to the action of the starch, 
both as to coherence and in the fire. But the binding power of the 
starch, though somewhat diminished, was nevertheless still very 
great, and it is probable that a briquet with 1 per cent of starch and 
8 per cent of a heavy crude oil, or a less percentage of oil residue, 
would prove satisfactory. It is possible that in some places such a 
combination might prove the cheapest and most satisfactory binder 
obtainable. Pitches did not seem to injure the action of the starch, 
but unless a small percentage of pitch is found to waterproof there 
would be nothing gained by the combination. The experiments 
made did not seem to indicate that a small percentage of pitch with 
starch would give satisfactory results in the weather, but this point 
should be tested on a larger scale. 

A patent for the use of starch as a binder was issued in 1858, in 
England, to John Piddington. He used 36 pounds of starch and 8 
per cent of water per ton of coal. 

The objections to starch as a binder are that the briquets do not 
immediately harden, and that they will not stand exposure to the 
weather unless made waterproof. The advantages of starch as a binder 
are its cheapness, its wide availability, the fact that it introduces no 
smoke, and the fact that, being nonvolatile, it holds the coai together 
well. 

As shown by the census report for 1900 the amount of starch pro- 
duced in the United States during that year was 297,803,139 pounds. 
Of this amount 247,051,744 pounds was made from corn as raw 
material, the average price of the starch being 2.5 cents per pound. 
It is of course not necessary that starch to be used as a binder be 
pure, and a far better idea of its cost for this purpose can be obtained 
by considering the cost of the raw material. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 39 


The raw materials available in the United States are corn, wheat 
and other small grains, Irish potatoes, sweet potatoes, cassava, and 
spoiled products containing starch. The starch from wheat and 
other small grains is more expensive than that from corn. Cassava, 
yielding 4 to 5 tons per acre and containing about 25 per cent of 
starch, offers a very cheap source of starch, but in the United States 
it can not be grown far north of Florida. 

In 1900, 231,106 tons of corn were used for the production of corn- 
starch, sis average price paid being $11.78 per ton. Corn contains 
60 to 65 per cent of starch. The factories extracted on the average 
53.4 per cent, and the cost of this starch in the crude condition is 
therefore $18.85 per ton. The only preparation necessary would be 
fine grinding. 

The price of raw cornstarch may be estimated at $20 per ton, 
based on the census report for 1900, and inasmuch as only 0.5 to 1 
per cent of this material is required to make a coherent briquet, it 
follows that the cost of starch binder of this kind per ton would be 
only 10 to 20 cents. The briquets would not stand rain, but would 
prove perfect if kept under cover. It seems that starch briquets, 
only slightly waterproofed, might be used during the dry season in 
certain sections of the West. If more thoroughly waterproofed with 
heavy crude petroleum oils they might be generally used. The crude 
petroleum would increase the fuel value of the briquet almost suffi- 
ciently to pay for itself. It seems, therefore, that further experi- 
ments with starch on a larger scale are desirable. 

22. Potato starch—Properly chosen varieties of the sweet potato 
contain about 22 per cent of starch and the yield per acre is large. 
Small, unmarketable potatoes may be used. The sweet potato is 
available in many parts of the United States. 

The Irish potato is widely distributed, and starch factories con- 
sumed 118,000 tons in 1900, paying an average of $5.90 per ton and 
obtaining an average of 14.3 per cent of starch. As a rule only 
unmarketable potatoes were used and this accounts for the low per- 
centage of starch obtained, the average yield of Irish potatoes being 
18.2 per cent of starch, and some varieties giving as high as 25 per 
cent. On the basis of 18 per cent available starch, the raw starch 
obtained from this source is worth $32.75 per ton. 

Usually, therefore, starch obtained from potatoes would be more 
expensive than that obtained from corn. A number of tests were 
made to see if the action of the two starches is similar. No difference 
in the coherence of the briquet or in its behavior in the water or in 
the fire was detected. 


40 BINDERS FOR COAL BRIQUETS. 
SLAUGHTER-HOUSE REFUSE. 


Slaughter-house refuse, which is now largely made into glue, has 
been so often suggested as a binder that its cost was investigated. 
The census of 1900 showed that 34,750 tons of glue were produced, 
valued at $155 per ton. The price is therefore prohibitive and no 
experiments were made with this material. 


TARS AND PITCHES FROM COAL. 


Preliminary considerations —The work done at the briquetting 
plant under the direction of Dr. J. H. Pratt had shown that there 
was great variation in the value of various coal-tar pitches for bri- 
quetting purposes. That work had also shown that coal-tar pitch 
would be one of the most important binders to be considered. An 
endeavor was made, therefore, to study the various grades of coal 
tar and the pitches therefrom, with the idea of improving the pitches 
and of establishing some method of examination which might reveal 
their value without the necessity of an actual briquetting trial. 

The total production of coal tar in the United States in 1903 was 
62,964,393 gallons, valued at $0.0349 per gallon, or $7.27 per ton. 

On distillation coal tar is divided into several fractions which are 
more or less clearly defined. By further distillation these fractions 
are separated more completely and find their way to the market as 
illuminating oils, naphtha, creosote, etc. They consist of a very 
large number of chemical compounds. The manner in which coal 
tar is fractionated varies at different works, but as illustrative, it 
may be said that the ammoniacal liquor distils first, then the first 
hight oils, boiling below 110° C. The second light oils come off at 
110° to 170° C., the carbolic oils at 170° to. 225°, the creosote oils at 
225° to 270°, the anthracene oils at 270° to 360°, and lastly the pitch 
is left behind as a residue. 

None of the oils coming off below 270° C. are useful in briquetting. 
The anthracene oils, which consist of a large number of different com- 
pounds, should not, however, be entirely distilled from the pitch if it 
is desired to use the pitch for briquetting. Nearly all the various 
constituents of both the pitch and the anthracene oils except the free 
carbon are soluble in carbon disulphide. Constam and Rougeot? 
examined 33 pitches obtained from various sources, and found the 
amount of carbon-disulphide extract to range from 60.43 to 91.22 
per cent and to average 76.3 per cent. They also found the value of 
the pitch for briquetting purposes to be proportional to the amount 
of carbon-disulphide extract. The results obtained by the writer 
lead to the same conclusion, except that the free carbon (that is, the 
insoluble portion) is believed to be not only inert but detrimental to 





a Zeitschr. f. angew. Chemie, vol. 17, no. 26. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 41 


the pitch, indicating that the increase in the value of a pitch for bri- 
quetting purposes is somewhat greater proportionally than the 
increase in the percentage of extract obtainable. The free carbon 
seems to prevent the pitch from spreading easily over the grains of 
coal, and owing to its very finely divided condition itself offers a 
very large surface for the absorption of pitch. 

A pitch has no true melting point, but owing to the large number 
of different chemical bodies which it contains, softens only very 
gradually. This softening point of the pitch has a marked influence 
on its use in briquetting, for the pitch must either be so brittle that 
it can be broken finely and mixed with the coal as a solid, or it must 
be melted and distributed as a liquid. Many pitches soften at so 
high a temperature that they can not be efficiently used except by 
heating above 100° C. The pitch must therefore be adapted to the 
briquetting machine in which it is to be used. Many methods of 
determining the softening point of a pitch have been suggested, but 
most of them are either too troublesome for practical use or not 
accurate. In the experiments here recorded the flowing point of 
the pitch was used as an index of the temperature at which it soft- 
ened. This point was determined by placing about 3 cubic centi- 
meters in the bottom of a test tube one-half inch in diameter and 
inserting the tube in a bath. The temperature of the bath was 
raised until, on taking out the tube and inverting it, the pitch flowed 1 
inch down the tube in fifteen seconds. 

In ascertaining the value or suitability of a given pitch or tar for 
briquetting purposes three determinations are necessary: 

1. The pitch or tar is distilled and all oils coming off below 270° C. 
are rejected as being of no value in briquetting. 

2. The flowing point of the portion to be used in briquetting is 
determined. This should generally be not less than 70° C. 

3. The pitch is extracted with carbon disulphide. The smaller 
the amount of residual carbon the more satisfactory the pitch. 

It should be borne in mind that the higher the flowing point of the 
pitch the more satisfactory it will prove in the fire when used with 
coals that do not cake readily. If the pitch has too high a flowing 
point to be workable with the briquet machine at hand, it could be 
softened by the addition of a high-boiling coal-tar oil (above 270° C.) 
or of very soft pitch. Coal-tar creosote could be used, but its boil- 
ing point is too low to make its use in all respects satisfactory. 

23. Blast-furnace tar.—As it was impossible to learn whether blast- 
furnace tar and the similar material known as shale tar are produced 
in the United States, no experiments were made with them. 

24. Producer-gas tar—Two samples of producer-gas tar were 
examined. The first, designated 24 C, after pouring off the water, 
gave on distillation, water, 30 per cent; oils below 270° C., none; 


49 BINDERS FOR COAL BRIQUETS. 


oils at 270 to 330° C., 6 per cent. From 330° the thermometer 
jumped suddenly to 370° and the distillation was stopped. The 
residue gave with Illinois No. 4 coal a satisfactory briquet when only 
4 per cent was used as a binder. 

The next sample, designated 24 D, was tested after boiling off the 
water. The result showed a satisfactory briquet with Arkansas 
No. 7 A coal when 4 per cent was used, but a larger percentage is 
necessary with most other coals and probably 8 per cent would be 
necessary for most lignites. 

The tar obtained, when freed from water only, is rather too liquid 
to produce the best quality of briquet. But the removal of only 
about 6 per cent of oils raises the flowing point of the tar to about 
70° C. and the residue appears, as above seen, to be excellently fitted 
for briquetting purposes. The amount of carbon-disulphide extract 
obtainable from the residue was not determined. It should not be 
large, for the temperature at which the tar is made is comparatively 
low. This is probably the cause of the superior binding power of 
the pitch. 

The amount of this tar obtainable and its market value are 
questions for future determination. 

25. Illuminating-gas tar—About 25 per cent of the illuminating 
gas produced in the United States is made from coal, and the tar 
resulting from the process amounts to about 5 per cent of the coal 
coked. The census report for 1900 gives the production for 1899 as 
67,094 tons. In 1903, 61.4 per cent of the coal tar made was pro- 
duced in gas works. The average value of this tar as distinct from 
other coal tars is not obtainable, and $7.27 per ton, the average value 
of all coal tars for 1903, is therefore ea pved as approxima correct 
for gas tar. 

This tar is too liquid to produce good briquets. The oils coming 
off below 270° C. should be disposed of. The residue, equaling 70 per 
cent of the total, would cost $10.40 per ton, if the sale of the low- 
boiling oils could be made to pay the expense of the distillation and 
the profit thereon. 

Pitches 28 A, 28 B, 28 C, 28 D, 28 E, 28 F, and 28 I, obtained from 
this tar, were examined, and the percentages determined as necessary 
to make satisfactory briquets are shown in the table (pp. 51-52). 

26. By-product coke-oven tar.—iIn 1903, 38.6 per cent of the total 
coal tar produced (24,296,536 gallons) was produced in by-product 
coke ovens. The census report for 1900 shows that in 1899 only 
3.33 per cent of the total coal coked was coked in by-product ovens. 
Consequently the amount of coal tar from this source could be 
enormously increased. 

This tar is obtained by distillation at a high temperature, and 
therefore contains more fixed carbon than tar from illuminating-gas 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 43 


plants. About 60 per cent of the tar from an Otto-Hoffman oven is 
pitch. 

The tar is too liquid to be used directly for briquetting. The 
results with pitches 28 G and 28 H, made from coke-oven tar, are 
shown in the general table (p. 51). 

27. Coal-tar creosote.—The principles governing the use of binders 
make it appear useless to test coal-tar creosote alone. It is too thin a 
liquid to make coherent briquets and of too low a boiling point to give 
satisfactory results in the fire. This creosote could be used to thin a 
pitch whose boiling point is too high, when such use is advantageous. 
It could also be used to waterproof a binder that would not stand the 
weather; but this could be done as well with a crude oil of low specific 
gravity, and the cost would be less. Coal-tar creosote is worth about 
6 cents per gallon. 

28. Coal-tar pitches —The pitch designated 28 A was obtained by 
Dr. J. H. Pratt, who called it pitch C in his report.* This pitch flowed 
at 100° C., and the behavior of the briquets in the fire was satisfactory. 

The pitch designated 28 B was obtained through Dr. Pratt and was 
by him designated, in his report, pitch D. This pitch had a flowing 
point of 127°C. It was used in making a very large number of tests 
on the comparative action of different coals with the same binder. 

The pitch designated 28 C was used to briquet 50 tons of Arkansas 
semianthracite slack, about 6.5 per cent being used. This pitch had 
a flowing point of 100°C. It proved too soft for use with a pitch 
cracker on a summer day. 

The pitch designated 28 D was used to briquet 200 tons of Arkansas 
semianthracite slack, about 6.5 per cent being used. This pitch had 
a flowing point of 120° C. and was sufficiently brittle for use on the 
hottest day. It gave a carbon-disulphide extract of 67.75 per cent. 

The pitch designated 28 E had a flowing point of 100° C. 

The pitch designated 28 F was very soft, having a flowing point 
of 68° C., and did not prove as efficient a binder as its appearance 
indicated. No further examination was made to determine the cause 
of the trouble. | 

The pitch designated 28 G was a soft coke-oven pitch obtained 
from tar produced in the Semet-Solvay process. It had a flowing 
point of 95° C. and yielded about 86 per cent of carbon-disulphide 
extract. 

The pitch designated 28 H was a harder coke-oven pitch from the 
same source as 28 G. It had a flowing point of 100° C. and gave 
81.50 per cent of carbon-disulphide extract. The.briquets were pos- 
sibly a little stronger than those made with the soft coke-oven pitch. 

@Preliminary report on the operations of the coal-testing plant of the United States Geological 


Survey at the Louisiana Purchase Exposition, St. Louis, Mo.,1904; Bull. U. S. Geol. Survey No. 261, 
1905, p. 134. 


44 BINDERS FOR COAL BRIQUETS. 


The pitch designated 28 I was received through Dr. Pratt, who 
called it pitch X in his.report.“ It had a flowing point of 190° C., 
being very hard and brittle. The carbon-disulphide extract was 63.2 
per cent. A large number of tests were made with this pitch when 
determining the qualities of binders in general in order to learn why 
this grade was so poor a binder. This seemed to be due to two 
causes—(1) the large amount of contained free carbon (36.8 per 
cent), and (2) the high softening point. At 100° C. the binder did 
not melt sufficiently to spread over the grains of coal to the best 
advantage. 

To test this latter point the pitch was mixed with wood creosote 
12 F, which did not itself possess sufficient binding power. Two 
hundred grams of pitch was mixed with 100 grams of the wood cre- 
osote and heated with stirring until thoroughly mixed. The resultant 
pitch, which was brittle enough to be pulverized if kept cool, was 
then tried with a number of coals and compared with the original 
pitch. The results from this mixture, designated 28 J, are shown in 
the table (pp. 51-52). It will be noted that in all the tests 4 per 
cent more of the original pitch than of the mixture was required, 
thus confirming the diagnosis of the trouble. 

None of the coal-tar pitches gave coherent briquets with less than 
6 per cent, and with many of them 7 or 8 per cent was required. 
The reason why a coal-tar pitch will not briquet if less than 6 per 
cent is used is that it contains a comparatively large amount of car- 
bon. The residue from producer-gas tar made satisfactory briquets 
with 4 per cent, and this result was doubtless due to the fact that 
such tar contains little free carbon. 

The cost of coal-tar pitch per ton may be taken as $11; therefore 
the cost of the binder per ton of briquets produced ranges from 66 
to 88 cents. The briquets when properly made will stand exposure 
to the weather well. They will stand up satisfactorily in the fire if 
the coals cake at all readily. With noncaking coals the briquets 
would not prove satisfactory in the fire. This binder does not cause 
an undue amount of smoke. 


NATURAL ASPHALTS. 


Asphalts grade almost imperceptibly into heavy, thick petroleum 
oils. The designations used by Eldridge? have been followed in this 
discussion. Wurtzilite, nigrite, ozocerite, and grahamite occur in the 
United States, but not in deposits profitable to mine. 











@Preliminary report on the operations of the coal-testing plant of the United States Geological 
Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904; Bull. U.S. Geol. Survey No. 261, 
1905, p. 134. 

b Eldridge, G. H., Origin and distribution of asphalt and bituminous rock deposits in the United 
States: Bull. U. S. Geol. Survey No. 213, 1903, pp. 296-305. 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 45 


30. Impsonite.—Impsonite, sometimes called grahamite, is found 
in Oklahoma. It softens at a high temperature, but does not melt. 
In carbon disulphide 35 per cent or more is dissolved. 

The sample tested was obtained through Dr. Pratt and was des- 
ignated B 4 in his report.* This was tested with a lignite, as its only 
possible use in briquetting was considered to be to mix with a non- 
caking coal in rather large percentage. From 20 to 30 per cent was 
found to be required to hold a California lignite together in the fire. 
Even though the material is very cheap, the large percentage required 
prohibits its commercial use. 

31. Gilsonte.—lIt is estimated by Eldridge that 32,000,000 tons of 
the asphalt known as gilsonite are now in sight in the extensive 
deposits that occur in Utah. He further states that the cost to mine 
does not exceed $1.75 per ton. The material has to be hauled a long 
distance to a railroad, and the present price in St. Louis is about $35 
per ton. Gilsonite has a brilliant luster, burns and acts like sealing 
wax, and is entirely soluble in carbon disulphide. Two samples were 
tested. 

The sample designated 31 A was black, with a brilliant luster, and 
flowed at about 250° C. In testing, the finely powdered material was 
mixed dry with the coal and heated far above 100° C. As shown in 
the table (p. 52) it gave a good briquet when 4 per cent was used. 

The sample designated 31 B was black, with a less brilliant luster. 
When its flowing point was being determined it frothed out of the 
tube. It gave a briquet of satisfactory coherence when 6 per cent 
was used as a binder. The briquets are also satisfactory in the fire; 
and, owing to the high softening point of the binder, it would be 
very useful with noncaking coals. At its present price of $35 per 
ton, however, even 4 per cent of this binder is out of the question. 

32. Maltha.—Small deposits of maltha, a liquid asphalt, occur in 
Oklahoma, Mexico, California, and Texas. In 1903 the only pro- 
duction reported to the Geological Survey was 58 tons from Texas, 
valued at $19.83 per ton. 

The sample tested was obtained through Dr. Pratt and was called 
by him “‘liquid Austin asphalt.” <A satisfactory briquet was pro- 
duced with 3 to 34 per cent of binder. Attention is called to the fact 
that when as much as 8 per cent of this binder is used the briquet 
grows weaker instead of stronger. This is due to the low flowing 
point of maltha, 58° C., which causes the briquet to crush easily if 
an excess is used. In the fire the binder would give satisfactory 
results only when used with coals that cake very easily. 





@ Preliminary report on the operations of the coal-testing plant of the United States Geological 
Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904; Bull. U. S. Geol. Survey No. 261, 
1905, p. 134, 


A6 BINDERS FOR COAL BRIQUETS. 


The cost of this binder, 3 per cent being used, would be 60 cents 
per ton of briquets produced. With some coals a larger percentage 
would be necessary. 

33 and 34. Refined Trinidad asphalt and refined Bermudez asphalt.— 
Considerable quantities of crude Trinidad and Bermudez asphalts 
are annually imported. In 1903 the imports of the former amounted 
to 129,133 tons, valued at $367,003; and of the latter 9,898 tons, 
valued at $48,218. 

The cans in which samples were furnished for these experiments 
were not marked and complete identification was impossible. The 
softer of the two samples flowed at 115° C. and could not be powdered. 
It gave a satisfactory briquet when 6 per cent was used with Illinois 
No. 11 C (4) coal. The harder sample could be powdered, flowed at 
180° C., and on testing showed a briquet that was hardly satisfactory 
when 8 per cent of the binder was used with Illinois No. 11 C (4) coal. 
If the binder had been superheated better results could probably 
have been obtained. 

These asphalts apparently could not compete with coal-tar pitches 
as binders. 

35. Hard and refined asphalts.—Bituminous sandstones, lime- 
stones, or shales occur in several States in deposits of considerable 
extent. These are mined, but usually the rock is used as a con- 
stituent of paving mixtures and the bitumen is not extracted. 
Attempts have been made to refine this rock either by distillation or 
by extracting the bitumen with a solvent, such as naphtha. The 
process does not seem to have been very successful commercially. 
The only production reported is 6,400 tons from California, with a 
value per ton of $21.87; and 877 tons from Indian Territory, with a 
value per ton of $17.61. Nosamples could be obtained, and the 
product is probably not now on the market. 


PETROLEUM PRODUCTS. 


36. Crude oil.—Unless they are of the consistency of maltha, crude 
oils are not suitable for binders, being too liquid. They might be 
used to advantage in waterproofing briquets made with starch, 
sulphite liquor, or molasses. 

37. Petroleum residuum.—There are many grades of petroleum 
residuum depending on the base of the crude oil (that is, whether the 
oil has an asphalt base, or a paraffin base, or an asphalt and paraffin 
base), on the temperature at which the distillation is stopped, and on 
the amount of cracking to which the oil is subjected during the 
distillation. 

In 1903, 46,000 tons of asphaltic residue, with an average value of 
$11.30 per ton, were produced from petroleum in California; and 


LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 47 


2,100 tons, valued at $14.16 per ton, were produced in Texas. If 4 per 
cent of this material were used as a binder, the cost per ton of briquets 
produced would be 45 to 55 cents per ton, making this binder one of 
the cheapest to be had near the oil fields, when the oil contains an 
asphalt base. Hvenlessthan 4 per cent could be used with some coals. 
For the best results, the asphalt residue should flow at 90° to 100° C. 

Six samples of asphalts were examined. The sample designated 
37 A was shown by test to flow at 100° C., and 99.38 per cent was 
soluble in carbon disulphide. The tests showed that except with 
the lignites, 3 to 4 per cent of this asphalt would give a satisfactory 
briquet. With caking coals it is satisfactory in the fire. 

Another sample was designated 37 B. With most coals 3 to 4 per 
cent of this asphalt would be required to produce satisfactory briquets. 

The sample designated 37 C was received through Dr. Pratt 
from Caspar, Wyo., and by him was designated B 6in his report.* It 
flowed at 95° C., and gave a carbon-disulphide extract of 99.88 per cent. 
A satisfactory briquet was made with 4 per cent of this binder. 

The sample designated 37 D was received from Texas, and was 
designated B 3 in Dr. Pratt’s report.* It flowed at 140° C., and with 
most coals about 6 per cent would be required to produce a satisfac- 
tory briquet. 

The sample designated 37 E, a California asphalt of grade B, was 
designated B1 by Dr. Pratt.¢ It did not soften sufficiently at 100° C., 
but if superheated a satisfactory briquet could be obtained with 8 per 
cent as binder. 

The sample designated 37 IF, a Texas asphalt, was designated B 2 
by Dr. Pratt.* It did not soften sufficiently at 100° C. When super- 
heated it gave a satisfactory briquet with Hlinois No. 4 coal, 6 per 
cent of binder being used. 

38. Water-gas tar.—The census report states that 75 per cent of 
the iluminating gas produced in the United States in 1899 was water 
gas. Petroleum oil is used in enriching this gas and is partly decom- 
posed in the process, resulting in the formation of water-gas tar, of 
which 48,714,324 gallons were produced in 1899. With an average 
density of 1.1, this would be equivalent to 222,868 tons of tar. The 
tar itself is too liquid for use, but a pitch made from it was examined, 
as shown in the next paragraph. 

39. Water-gas tar pitch.—The sample of water-gas tar pitch fur- 
nished to Dr. Pratt was by him designated pitch H.? It flows at 92° 
C., and with some of the coals 5 per cent proved sufficient to produce 
excellent briquets. The carbon-disulphide extract was 88.10 per 
cent. With caking coals the briquets are satisfactory in the fire. 
This pitch is worth somewhat less than coal-tar pitch, its value being 

a Preliminary report on the operations of the coal-testing plant of the United States Geological 


Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904; Bull. U. S. Geol. Survey No. 261, 
1905, p. 134. 


48 BINDERS FOR COAL BRIQUETS. 


given approximately as $10 per ton. The cost of the binder per ton 
of briquets produced would therefore be about 50 cents, effecting a 
saving of at least 20 cents per ton over the use of ordinary coal-tar 
pitch. 

40. Wax tailings.—A product known as wax tailings was received 
by Dr. Pratt. It is soft at ordinary temperatures and pulls into long 
threads. It melts to a thin liquid at about 70° C. As low as 3 per 
cent gives briquets of satisfactory coherence and these are also satis- 
factory in the fire if the coal cakes readily. The briquets could not 
be subjected to any pressure in the fire, and would yield to pressure 
if placed in a warm place. It is doubtful if they could be piled in a 
very hot sun. The yield of this product is said to be moderate in 
amount. The value is 6 cents per gallon, or about $15 per ton, and 
the cost of this binder would therefore be 45 to 60 cents per ton of 
briquets produced. 

41. Acid sludge.—Tests of a sample of acid sludge showed that 10 to 
12 per cent was necessary to make a coherent briquet. This material 
was distinctly acid with sulphuric acid. Its value could not be 
learned and therefore no further experiments were tried with it. 

42. Asphalt tar.—The product known as asphalt tar, as obtained 
by Dr. Pratt, was a rather thin liquid which poured readily and pro- 
duced briquets that would crush easily and would not stand up satis- 
factorily in the fire. This tar, if its price permitted, might be used 
for waterproofing briquets made with soluble binders, as starch, sul- 
phite liquor, or molasses. 

43. Puntsch gas tar.—Pintsch gas tar, produced by the heating of 
petroleum oil in iron retorts to a high temperature, is obtained as a 
thin emulsion in water, being too thin for use asa binder. As it is pro- 
duced only in very small amounts in the United States, its further 
examination was deemed inadvisable. 

44. Pittsburg flux.—The substance known as Pittsburg flux is 
made by heating petroleum residuum with sulphur. The sample 
tested was tough and sticky, would cut easily, but would not pull 
into threads. It melted to a thin liquid at about 195° C. In testing 
it was mixed with Illinois No. 11 C (4) coal and heated far above 
100° C. It produced a satisfac tory briquet when 8 per cent was used. 


ADDITIONAL EXPERIMENTS WITH MIXTURES. 


All the briquets made with inorganic binders were brittle, though 
very hard. Experiment had shown that when brittle pitches, etc., 
were used, the briquets became less brittle if a thinner pitch or oil 
was added. Therefore an attempt was made to improve these 
briquets by the addition of organic binders. For this purpose coal- 
tar creosote (27), asphalt tar (42), and water-gas tar pitch (39) 
were chosen. The results are shown in the following table: 


e LABORATORY INVESTIGATIONS OF VARIOUS BINDERS. 49 


eres of briquetting California and Illinois coals with varying mixtures of organic and 
inorganic binders. 

















Binder. 
ames To) Upaiey iy ior ye : : Grade of 
Cont, Inorganic constituent. Organic constituent. Achers 
Per Por! Pe 
Material. nari, Material. epid! 
Plaster of Paris: 2 9.025... 6 | Coal-tar creosote.......... 4 3 
Meera ere tae epee Gules phAlG baPectecs cadence. 4 4 
Cea eit dale aes 6 | Water-gas tar pitch....-.. 4 4 
Portland Cement sts .t.-2 6 | Coal-tar creosote.......... 4 3 
Tlinois No: 6 B........ RA gat hayes alg a Ta GARD halpgaldeoscash alteske 4 3 
pee Ten eee eS oe 6 | Water-gas tar pitch....... 4 4 
Magnesium ORIG AG aase ss 2 | Coal-tar creosote.......... 4 3 
CMOmdeeeye Peal. Fas. vats 20) ASPHAalt arcs we toe ee 4 3 
WOO Ree ee las Deki wk bree 2 | Water-gas tar pitch......- 4 34 
Plaster “i arias: ceceee OF ee GOigk seta ceases eo ee ae 8 44 
: : ortiand cement.-....... Oulne ase LO JAR o's has Sates os ee 8 44 
California No. 1....... Magnesium oxide......... Stel Beer GO. wks aed. Se eee 8 4 
= (0 Faget a pe Ce eae Aiea ses LOI 5 eelecrae ee aS ei 4 3 

















a See p. 22. 


The briquets made with Illinois coal and water-gas tar pitch were 
fairly good and stood up very satisfactorily in the fire. The ad- 
vantage gained, however, over the use of the water-gas tar pitch 
alone would not be sufficient to offset the introduction of the 6 per 
cent of ash with the cement or the plaster of Paris, or the cost 
of the magnesium oxide when that material is used. The cohesive 
force of the briquets made with the two binders was no greater than 
the sum of the cohesive force obtained with each separately. The 
only advantage to be gained by using such mixed binders would be 
an added strength in the fire. Experiments with the California 
lignite were therefore made as above shown. The briquets were 
found to be considerably improved as to their behavior in the fire 
by the addition of the inorganic constituent of the binder. Briquets 
from this coal made with pitch alone fall to pieces badly in the fire. 
The improvement in this regard, however, is offset by the added 
expense and the introduction of ash, and it is therefore considered 
more desirable where possible to mix such noncaking coals with 
caking coals before briquetting. If this is not practicable then the 
addition of inorganic binders might be tried as a last resort. Should 
the inorganic binders be used, magnesium oxide and plaster of Paris 
will be found to give the most satisfactory results, 3 per cent of the 
former being equivalent to 5 to 6 per cent of the latter. 


98315°—Bull. 24—11—_4 


50 BINDERS FOR COAL BRIQUETS. 4, 


EXPERIMENTS IN BRIQUETTING WITHOUT BINDERS. 


Many experiments were made in the endeavor to obtain briquets 
by heating the coal without binder and then pressing. It was found 
that if this heating was done in a clay crucible as usual, coherent 
briquets could not be obtained. But if the heating was done in a 
small nickel crucible and the pressure applied before the coal was 
allowed to cool, briquets having considerable coherence were often 
produced. If the coal cooled after it had softened or commenced to 
cake, a coherent briquet could not be obtained, and even on again 
heating the coal it would not cohere in the press. This fact has also 
been noted by C. C. Catlett. It was undoubtedly because of the 
necessary chilling of the heated coal in taking it out of the crucible 
that better results were not obtained by this method. The experi- 
ments show the necessity of heating the coal under pressure if briquets 
are to be made without a binder. The German presses for briquetting 
lignite coal without a binder, which heat the coal by friction produced 
in the molds, are undoubtedly based on the right principle. 


RESULTS OF TESTS IN BRIQUETTING DIFFERENT COALS. 


The results of the tests here reported should be interpreted in con- 
nection with the detailed discussion of each binder. Thus while 
binders 12 D, 13, 25, 26, etc., mentioned in the table which follows, 
are too liquid for use as a binder, the pitches or tarry residues left 
after distilling off the low-boiling oils from these binders will make 
excellent briquets, as has been already pointed out. It should be 
remembered, moreover, that the degree of fineness to which the coal 
is powdered, and also the temperature to which the mixture of coal 
and binder is heated, will affect the character of the briquet and the 
percentage of binder necessary to make it coherent. Doubtless an 
uncontrolled variation in these factors has caused individual results 
to vary, but probably not to such an extent as to affect any important 
conclusions to be drawn from the work. 

Although many of the binders were tried with only one coal, the 
result permits the approximate prediction of the percentage of binder 
for any other coal in the table. It is not possible, however, to predict 
‘with the same certainty for the lignites, which show at times 9 varia- 
tions not susceptible of easy explanation. 


a Eng. and Min. Jour., vol. 71, 1901, p. 329. 


RESULTS OF TESTS IN BRIQUETTING DIFFERENT COALS. 


51 


Results of tests in briquetting different coals, showing percentages of binder necessary to 
make a satisfactory briquet. 


Designation of binder. 











Material.a No. 
i) 2 
GLEN 24 ee ae ie ae eae 1 
(MGONESEL s :o:0 a: ae 22558 3 
Magnesia cement b..... 4 
Plaster of paris....-.-- 5 
Portjand cement....... 6 
Natural cement........ 7 
Weer ClASS....«-252--. 9 
(212) 1 Pe ee ft ee op 10 
oS) aR Se San a pet 11 
Wood-tar pitch.......- 12 A 
12 B 
Pine-wood tars......-. 12C 
12 E 
NaF ey eee Oa a 14 
Sulphite liquor.......- 16 
WOTHBtATCh ena. =: = 5 21 
Potato starch......... 22 
Producer-gas tar pitch.| 24 C 
Producer-gas tar.....-- 24 D 
28 A 
28 B 
28 C 
28 B 
- 2 
Coal-tar pitches. ...-...- 98 F 
28 G 
28 H 
28 I 
28 J 
CR Aol Se ee Oe ae 32 
ny Anas 
37 C 
Petroleum residuums ..)/{37 D 
37 E 
37 F 
Water-gas tar pitch....} 39 
Waxibailinesa 2... lt 40 
ANCTOU TV Cle ea ene 4l 


Field designation of coals and lignites briquetted. 






























































Ar- | Cali- | aojo- Illinois. 
kan- | for- 
OM IN ican "9 Aes ea g. |9 A. }10./11 B 
PAS ti ie . . . . . . . . . . 
3 4 5 6 il 8 9 10 il 12../-1814 
8 Sia perce oho retains CI ere "a | pe Heh MRS AR Lie fl | el He a aed 8 
2. RM Cnt Sg ope tg RIB | SAAN RIE Ate get ore elo eteg ea sll rex nclin Coss tate el eet $ 
oof PRR le a WS an ee el aa I ee Ip” 4 
1 A LOR TRS ee ae oa) ee A'S Ee eae or (ey <a Wee IS 1 ve 
2 aha RL RS | sop toe al | Aare I aah |) re. De ae lies IDA (a BARD mil ie Im (a 12 
ae aS RE te ee ae I eae | ee STE dm Oe CA Re De mI Oe 14 
2 aN a S| ek ol | eae aie 3 es ay cae akc 9 OY A aU a pay 14 
6 Gale te sete en ts ae i fs aeeee | (eek © Oe ea Rei es 6 
3 | lA oe lt aba tb oe Ce le Sl LA ie lpia) eA ie 3.5 
8 51h | Ne eee eee eee n (vy eas VER” a he a ae ene pelt 10 
3 re pi | emi nd be 4 3) Mets 5 5 4 3.5 
4 NS ie Se eee es (eee 5 re die: Saag 5 5 5 4.5 
AS. poh, A ean ed |< arian | ie anki | eae SEE NRE PY" AR mR I TM pa gL 
mig bie Bee. Ge RM 9 A Ce aoe (ARUN a eS Se Ses See NCS oy Sr et eet IN eek 
ee Dis Ae este sale eae UD) eee? Ee RIL) Pe cemetery Caren 
0.5 1 hai ee LSS SO ee AN Maes Hey dt 0.75 
a) 1 HG 5 aN fad AL eit e ses, See ae en est Se 15 
SOE So UREA ater Se 4 Peel 2 SAS Ts RR ae emu | Ae BAS ae IB Sana a HA, 
COL Uk, Salk oe | PM ME EITC a tea RT SATII Rare |S eM Pe co) at te a 
Dien hho SMe oe eid oo * I a 4 fg | he Sacer S| ee Fe eT (UR 7 
8 1 a 12 ies OR SAS INR Cte Bett Sy 
i a ape Ree 8 ras SP A Te Le YR «ole |S ge pee | PR Ue ea Ma | VR 2 A 
DUR eee lacie ce cer Bo Ne Saeki clab is ceiclcc Sets cll ete cenesl Ceee Sain sa aes cael ek 
ee Poe eta EIS clo oles (6 pee ee a Peta Sea a ar atl fs ccd cil coher cic an oe eee eae 
ee. 5 Se aee > ae 2 eee 8 Pe ee al SS |e ee ee eR ep eek SU Uerg. fo 
2 Sie 5 hei ts) ab acpi, A ee ee Neal 6 hap dtas| a peiia erated ete im wis oil ave Bema etllassrecs, oll te cla Stet aie eae aa eee 
ere yeni) (ie ge a Me a 6 Bee eee Bie EON Pay ah ls Cae dita <5 Ae WL LY apo de 
TA ec, 3 V1 Par te ecasly peel (let 16 bE: is | Ae eater 16 16 T6115 
Ce Ate Net || ae Gite ser 12 LORS 12 12 Lip tt 
Leas eine ae a ey Ys creas 3 lS eee cane AAS | Seu ee RS Seam seh SMC Ee ey 
3 igi Ae OS a Wl ee nga pg tester VA Ee (hea le Sil cee Oe | el a 4 
ee len 48, Se eyes 2-5 Baye (ee eee ee rH pepe RH) Sle BI cee ta Cake © ere \ RC ea 4 
PONE ENO TS a ee AOS Selb RAS IE ORGS ARGENT Sn 2S Clg ARNG AP 
| Sees he es Sener oe aie LMM NE ee ae eae cps RrePeC LS, eet tar lll Metce atal ere NIe teal tale cls Sroles 
Tee) oie mee Ae |b ai a 6 BEES eave ect oea ey A te es iene aL ate eee y= eee rats 
4.5 Foie et ee 6.5 6 5 6) 6.5 6.5 6 5 
me eet steno | ORC a Ge Pee © oR FUE ee Aael e (e beg Fee es et chee 
12 1 Val ES Se alk pa la BC: Wa etc VOI Nf NO I pot Lb 

















a The following materials were found to be of no use as binders: Lime (2), slag cement (8), wood 
pale (15), beet pulp (17), lime cake (18), and impsonite (30). 
inder were: Pine-wood tar (12 D), pine-wood creosote (12 F), hard-wood tar (13), illuminating-gas 
tar (25), by-product coke-oven tar (26), coal-tar creosote (27), crude oil (36), water-gas tar (38), asphalt 


tar (42), and Pintsch gas tar (43). 
(19) and cane-sugar molasses (20). 


b Contained sufficient magnesia to make 4 per cent MgO 


Those found to be too liquid for use as 


Satisfactory briquets were not obtained from beet-sugar molasses 
Blast-furnace tar is not produced in the United States. 


52 


BINDERS FOR COAL BRIQUETS. 


Results of tests in briquetting different coals, showing percentages of binder necessary to 
make a satisfactory briquet—Continued. 





Designation of binder. 


Field designation of coals and lignites briquetted. 








Material. No. 
1 2 
CIBY 2.5 Shek bee eee 1 
Magpnesia- ..etntegs asa: 3 
RoOsith. Save ceo 10 
Pitch? 42 seneeeeee eS 11 
Wood-tar pitch ....... 12 A 
Pine-wood tars ee 
Brats ts 12C 
Cornstarchiie. ce scerns 21 
Potatostarch.2-2...00% 22 
Producer-gas tar.....- 24 D 
28 A 
Coal-tar pitches....... | ze a 
28 fe 
: A 31 
GuisOnites. on. 2... sees 131 B 
Refined asphalt ......- oar 
37 A 
Petroleum residuums..|;37 B 
37 C 
Water-gas tar pitch...| 39 
Wise balling s i222 oe 40 
IUCIOISHIC POO. Wenn 2k crt 41 
Pitts burp Tux Ss. ce ee id 





















































Okla- 
homa. 








wee ee eee 


ett ee eee 


see ee eee 


llinois, | Indian wo. | a New | North 
ayia Terri- | Iowa. betes Mexico. | Da- 
tory. 2 cee kota. 
uc(4)./14.; © 1.| 2 
15 16 17 18 19 20; 21 22 
oes Camis Se, ge oa Meee eye ls oe A ee 8. 4a ee 
Bye eas Bee tl et hasan ala | Semana a0 “22 ee 
GB Vl he AE Sele ee na ae 6.) ee 
ee hank aH Aes Ee REI chon See lor eteeee & ah, > OM a eee 
19 cis eA de th cpadL aes 412 itcoo eae 
S Gi tilec aA ANS acest bent echt paren 6 10 
5 OL 3.5 SS A a Rae ee 
el ete La Ricterat ao eaten ee eee bo od. | Bisa 
Di GA SRS Rta oa Eo amen a a eas Lo) ae oh. 25 See 
CE) Res Meee Se a OR i RMS AEE aE A 
0B) RRA. Sada cGy a He et SE ae ee ee Se 
DON cintnelis oe eke 8 8 8 | 14/8 16 
RET Ae Cel ey Sei pee): A 16) eo. cee 24 
RBS Ae De pmb cts otal en tek oly Oe stare terre heeled le actt avestit Sale a 18 
Be eee Ae, es SC OO EEN eh ee a 
Owe. SAwck oe loose cee ale co oo dherc ts een ea 
Oi Py AC eS Ol ea ek ae ee Ss Se eee 
Bay inne crclallISete tage ave whale stare kee germ oes |e ee ee 
BS PSC Gis Lae Ste HONS IE fem mabe: 3 MPA WR A eek 
Bo Node eae te weber oe tee ootece 2 ol. eae 
PTO ree errs pe NORD DS aes) fr ee Eee Oe elie Ae Be Beg 
6 6. eck slew be atieee. ob Oh oo ee eee 
Ao ode iets laterchs so Mepis pie a SRW She ae otek lc are ee 
As his jovetear es dnc See a Shs Se ere ie | i ea 
+S PE) Pmemree! (sister ideals 12 (mies bdiirs hap aemkten Gad Rae el Se pe ele et 























eee ele wee 


eee ele wee 


GOVERNMENT PUBLICATIONS ON BRIQUETTING. 


The following reports (except those to which a price is affixed) can 
be obtained by application to the Director of the Bureau of Mines, 
Washington, D.C. The priced publications can be obtained by 
sending the price, in cash, to the Superintendent of Documents, 
Government Printing Office, Washington, D. C. 


PUBLICATIONS OF THE UNITED STATES GEOLOGICAL SURVEY. 


Butuetin No. 261. Preliminary report on the operations of the coal-testing plant of 
the United States Geological Survey at the Louisiana Purchase Exposition, St. 
Louis, Mo., 1904. E. W. Parker, J. A. Holmes, M. R. Campbell, committee in 
charge. 1905. 172 pp. 10 cents. 

PROFESSIONAL PAPER No. 48. Report on the operations of the coal-testing plant of 
the United States Geological Survey at the Louisiana Purchase Exposition, St. 
Louis, Mo., 1904. E. W. Parker, J. A. Holmes, M. R. Campbell, committee in 
charge. 1906. In three parts. 1492 pp., 13 pls. $1.50. 

Buuuetin No. 290. Preliminary report on the operations of the fuel-testing plant of 
the United States Geological Survey at St. Louis, Mo., 1905. J. A. Holmes, in 
charge. 1906. 240 pp. 20 cents. 

Bu.tuetin No. 332. Report of the United States fuel-testing plant at St. Louis, Mo., 
January 1, 1906, to June 30, 1907. J. A. Holmes, in charge. 299 pp. 25 cents. 

BuuueTIn No. 385. Briquetting tests at the United States fuel-testing plant, Norfolk, 
Va., 1907-8, by C. L. Wright. 1909. 41 pp., 9 pls. 


PUBLICATIONS OF THE BUREAU OF MINES. 


BULLETIN 14. Briquetting tests of lignite at Pittsburg, Pa., 1908-9, with a chapter 
on sulphite-pitch binder, by C. L. Wright. 1911. 61 pp. 11 pls. 
Bu.uetin 24. Binders for coal briquets. 56 pp. Reprint of United States Geo- 
logical Survey Bulletin No. 343. 
53 



























oe Teas 
yt, 
i i Vb Mee ie) 
oO i bh hal A AA) teat ier) rots CA Yi. cay “7 


: § ; ’ ; rey Be * w' PL 7 
CRC UE G5 yes 108 yy ost hepen voy) * t Ato 


, bi gealbide auld: Ry wodonech extd ae bgt a qi 





tpQHh Bea aeginGk cl i} 
¥ 1 ke ret Ds *} } ; hi : 7 
CY eTRES Otc, ULL publdirge Rasy nied | a AR 
b > AY ad +f ' 1 ” 
? i 4 {} M Siar i “Pity 7 fF , ft ; ai ica i iM qe e 75 1?) ate a 4 th bse » .) 


} i er 
Ty eA) rosea 4 4FRe) dine 


t 


CSNY FAD CES Ae | 





CAV Bs ee 8 A i+ 
‘ ni rf q 
si deli hs asad Wades eas a seh ax an nae nei a ea iam cetanale 
be ‘a , , J ay. sa | " b 
in Poe nae arity ‘igen nul Koy ME uy Larailystoesty ; 
vii 4 +) "4904 3 fa 1 ie Any SEL gh Ag mo at up. Rie. © 
j : ' t hy a4 a) oy h 
7 ee A Tee 
- sat, " 77) eee iT wis Le a7 V Mater 
‘ ~ bd ’ 
Patan unk) ah Koy ute’, eka ENR AS A 
f t EAP it ‘ Ld y ‘ , f, a Pe 4 free 
“a Ye uk og ie BVM ‘wae et ; 
parti) mea dhe Hustla aiieleenG Bal Re SST, Ee foetal 
; ‘ : ? A on j j ri 4 ‘ 
ay ie er) ae ) 38 Ae RE Lsigolonn? tony 
- W Lad 
altar, OF ‘ 
th whore ee toe Beant sedan Nai h URE ake TM Gait ] vi i 
‘ se: SUR cinta ahs ete RE le ee ‘pani 
Ber?) disks; yadmornent axtealt batt ora hiaim pate 
Se «tb. 4" adie 5D 
aly © qe TR: AO, ai a 
. 
atl tes. “FACTO SEE a eee ati ii 
SY CDE We RATA BT ; 
wee mee Vira ew et ia aa, 
| Ray Wee eh tee Aya i 
ve wn ¥ shu) ko fours i a ( eo A eIRINY 5 eat we? ¥ He 
Pia aA i 
+ 
i ty 3 





INDEX. 


iA. 
Page 
Absorption by briquets, per cent of....---- 10 
Acid sludge, investigation of...........- 48, 51, 52 
Arkansas coal, briquets from............... bl 
Shh, CBIR RES WO) Foi sr re 12 
Agpualt investigation of )....5.......-.-- 6, 44-46 
Asphalt, refined, investigation of..........- 46, 52 
Asphalt tar, investigation of..........-..-- 48-49 
NED 
ep reteatre We. OM DIMGGTS ss: 2.5.0 es ihe snes - 19 
Beet pulp, investigation of...........----.- 36 
CTEM G(R TAN Sy Se se a ee 53 
MUSTO MARION GOL fle noe eels cect ese e end 17-21 
amount of, determination of.......-.--. 21-22 
effect of, on coherence............--- 8 
HEUTEISMOWING. $75. to cn wi cue Apes 19 
relation of, to fineness of grain.....- 17-19 
Cope contol Voids: .25.--222-/-. 19-20 
Jorslacya lepers 00 hold i ty: a ne ae 16 
moans Of, tmickness Of ../..-....--.2... 20-21 
conditions governing use of.......---.-- 13-21 
(ean Oi 5 a ee eee 8, 13-14 
Stlecwol, Ol PIIQUOLS: ...-S2-.2-<\e0¢--5-2 14-16 
insolubility of, necessity for.....-.-.-.-- 10, 16 
physical relation of coal and...........-. 15 
CESS CE GRE) Gye (6 1) 5 ie eS 14 
Cade 2hyb) Gs Oh ON ee 6-8, 22-23 
TNGeMeAcIONS OF. ooo ts een 23-49 
Binders, inorganic, advantages and disad- 
WMATUASCS Ole hoo teehee out ee 23-24 
MINOGUE ADO: Olsyaets oso. <0 422+ See ee 24-29 
Binders, organic, investigation of....-....-- 29-48 
Bitumen im coal, per cent’ of... ...-.---.-.- 21 
Blast-furnace tar, investigation of.....--.- 41 
iBrigtetspaGvantagesOL. 2.2.0) soyé ol. 5 2. 5-6 
GHakActeriscics OL! SU. 2k. eles 52.22 8-13 
Siero OiNGeTS ONies isso eke. bess cecle 14-16 
EPIC LO Olen oki sce Gort soe cee 6 
OPER Cade 1) (GC Rag sa a 8.13 
THRGESINS) Gp pe, WS a a 50-52 
Briquetting without binders, investigation 
CTY sins SE ee 50 
Burning qualities of briquets, data on...-. 10-12 
C. 

SE TES PSU GGY tg SN a 11-12 
California, binders available in ............ 6 
California. coal, briquets from......-....... 51 
memilary pores, etfect ofs5.2.....2.0..---..- 18 
eaplett, ©, ©..0n briquetting. ....5...-----: 50 
Cement, natural, investigation of........ 28-29, 51 | 
Cement, Portland, investigation of......... 28 
Cement, slag, investigation of.......-...... 29 
Clay, investigation of..............--- 24-25, 51, 52 








Page, 

Coal, disintegration Of 15 a2. 2). gas ces coee ee 5 
physical relation of binder and......... 15 

Coal-tar pitch. See Pitch, coal-tar. 

Coherence, curve of, figure showing......... 19 
ASterminaTONOls 2 sae Uae. eeu 22 
MECC LOLA ATs Hee eae ee ak Rg Ea 8 
POSTLOL ep st cnrer ve ayee Ace cet le nel re AER 8 

Coke breeze, briquetting of....:............ 26 

Colorado coal, briquets from.............-. bl 

Constam and Rougeot, experiments of.. 15,21, 40 

Cornstarch, investigation of.......... 37-39, 51, 52 

Creosote, investigation of............- 31-33, 48-49 

Creosote, coal-tar, investigation of......... 43 

Dy 
Density of briquets, degree of.............- 9 
E. 

Eldridge, GH. on asphalt... 2. ue. 44 
Evaporation results, minimum of.........- 12-13 
F, 

Fir tar, investigation of ............-.--4-- 33-34 
G. 

Gilsonite, investigation of 22. 5.4....6 .068 45, 52 


Grains, size of, relation of amount of binder 


CFIC HLS (Qe Ee te Oe Oe seal tea be RR A 17-18 

Gurlt, A., on magnesia cement............- 26 

Bly 

Hardness of briquets, degree of............. 9 

Heating, effect of, on briquets.............. 16 

Heating values, magnitude of.............. 12-13 

lis 

Minors coal briquets from: ie eseteyaee ae 51-52 

Indian Territory coal, briquets from....... 52 

Towa coal; priquets fromlojo.2-2- sees lees ee 52 

Ipsomite, investigation of.........-...-.... 45 

bs, 

Laboratory investigation, review of.-..-.-.--- 21-49 

Ligsniteehriqueccing Olseeeeaacies seas eso 7 
briquetting of, amount of binder re- 

CUUTEG LOPSe ewes eet tee 18 

TAMEMUAVEStIP ATION, Olea occa setts tit erates 25, 30 

Lime cake, investigation of....-.-.-.------- 36 

Loze, E00. cost: OF briquets oof. scans oc 13 

M. 

Magnesia, investigation of......... 25-26, 49, 51, 52 
PROGUCTIONCOLe sscem et setse sate eu ates 25 
MISO OL Peele a aie eee paes Crete oe ikts, weet ile erste 7 

Magnesia cement, investigation of....-.. 26-28, 51 


55 


56 INDEX. 
Page Page 
Maltha, investigation of................. 45-46,51 | Slaughter-house refuse, investigation of..-... 40: 
Missouri coal, briquets from) 2e oe cesses ee 52 | Smoke, production of. ies. eee eee 11 
Molasses, investigation of.................. 36-37 | Soot, effect of, on binder required.......... 18 
N Starch, investiga tion\ofs. .2. tea eeeeeeeee 7, 37-39 
production 012.233 2e. ee. eee 38-39 
New Mexico coal, briquets from ............ 52° | Steel, A. A., work Of). 22s 5 
North Dakota, briquets from.............. 52 | Sugar-factory residues, investigation of.... 36 
0 Sulphite liquor, investigation of....... 7, 34-36, 51 
: Sulphur, eliminationsoly2 see Soo 23 
Ok in VOStea Clore cls) cn te ee oe eee 38, 46 
WAterproolne. Ovo cle e2.. ten eee 38 Zl. 
Oklahoma, briquets from..... eects eeee eee 52 | Tar, use of... ¢.-psuyeau ee 6 
Pp. Tar, asphalt, use Off... ee eee ree 48-49 
Tar, coke-oven, investigation of............ 42-43 
Petroleum products, investigation of......- , 46-48 | Tar, fir, investigation of................. 33-34, 51 
Petroleum residue, investigation of... 46-47,51,52 | Tar hard-wood, investigation of........ 33, 51, 52 
Pine-wood tar, investigation of............- 31-83 | ar, illuminating-gas, investigation of... .. 42 
Pintsch-gas tar, investigation of........... 43 | Tar, pine-wood, investigation of...... 31-33, 51, 52 
Pitch, investigation of..--...--.--.--- 30-31, 51,52 | par, Pintsch-gas, investigation of.......... 48 
Pitch, coal-tar, availability of, test of...... 7 | Tar, producer-gas, investigation of......... 6-7, 
INVESLIPE TION OLl ules ee. vera ce 6, 43-44, 51-52 41-42, 51, 52 
Pitch, producer-gas tar, use of......-...-- 6-7,51 | Tar, water-gas, investigation of............ 47 
Pitch, water-gas tar, use of....... 6,7, 47-49, 51,52 | Texas, binders available in................. 6 
Pittsburg flux, investigation of............- 48,52 | Toughness, binders imparting.............. 15 
Plaster of Paris, investigation of......-- 28, 49, 51 
Portland cement, investigation of......- 28, 49, 51 V: 
Potato starch, investigation of.......... 39, 51, 52 
Pratt) 7. H.. aid bison  ee 5 | Voids, per cent of, relation of, to binder re- 
Pressure, effect of, on coherence.........-.- 8 quired... [0000.0 SER a eee 19-20 
Publications; listote ane cee eee 53 
W. 
a Wagner; J. R.; on binderso sce: see 18,19 
Richardson, Clifford on binders............ 20 | Water glass, investigation of............... 29, 51 
Rosin, investigation of............... 29-30,51,52 | Waterproofing, need fors2c2 cu. de eee 10 
g Wax tailings, investigation of......... 6, 48, 51, 52 
; Weathering, effect of..................02.-- 5,10. 
Schnorr, Robert, on cost of briquets....... 13.|}-Weéry,; M!, experiments Ofeie nee 8 
Size and shape of briquets, data on......... 9 | West Virginia, briquets frome.y sie... 2 eee 52 
SIACKIOCCIITCHCE Of ae era ee Un eka 5 | Wood products, investigation of........... 29-36 
ALiiza tlomOhs cause wer aera Serine eae. 5-6 | Wood pulp, investigation of--2) see 34 





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